diff --git a/src/libdredd/src/mutate_ast_consumer.cc b/src/libdredd/src/mutate_ast_consumer.cc
index 568e5ea1..535e5582 100644
--- a/src/libdredd/src/mutate_ast_consumer.cc
+++ b/src/libdredd/src/mutate_ast_consumer.cc
@@ -397,7 +397,7 @@ std::string MutateAstConsumer::GetRegularDreddPreludeC(
   result << "#elif __APPLE__\n";
   result << "#define thread_local __thread\n";
   result << "#else\n";
-  result << "#include <threads.h>\n";
+  result << "#define thread_local _Thread_local\n";
   result << "#endif\n";
   result << "\n";
   result << "static thread_local int __dredd_some_mutation_enabled = 1;\n";
diff --git a/test/single_file/add.c.expected b/test/single_file/add.c.expected
index a2d5c0e9..4af6d6c2 100644
--- a/test/single_file/add.c.expected
+++ b/test/single_file/add.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add.c.noopt.expected b/test/single_file/add.c.noopt.expected
index 387298b4..b933fe31 100644
--- a/test/single_file/add.c.noopt.expected
+++ b/test/single_file/add.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add_float.c.expected b/test/single_file/add_float.c.expected
index 87b029ea..63d999b8 100644
--- a/test/single_file/add_float.c.expected
+++ b/test/single_file/add_float.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add_float.c.noopt.expected b/test/single_file/add_float.c.noopt.expected
index 6c38264f..e762a369 100644
--- a/test/single_file/add_float.c.noopt.expected
+++ b/test/single_file/add_float.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add_mul.c.expected b/test/single_file/add_mul.c.expected
index aebd5bb9..26466417 100644
--- a/test/single_file/add_mul.c.expected
+++ b/test/single_file/add_mul.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add_mul.c.noopt.expected b/test/single_file/add_mul.c.noopt.expected
index a4755b30..430206dd 100644
--- a/test/single_file/add_mul.c.noopt.expected
+++ b/test/single_file/add_mul.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/add_type_aliases.c.noopt.expected b/test/single_file/add_type_aliases.c.noopt.expected
index d8c6b88e..e2537725 100644
--- a/test/single_file/add_type_aliases.c.noopt.expected
+++ b/test/single_file/add_type_aliases.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/assign.c.expected b/test/single_file/assign.c.expected
index 10067ec9..417740ab 100644
--- a/test/single_file/assign.c.expected
+++ b/test/single_file/assign.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/assign.c.noopt.expected b/test/single_file/assign.c.noopt.expected
index 1c42ba68..d231959b 100644
--- a/test/single_file/assign.c.noopt.expected
+++ b/test/single_file/assign.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/basic.c.expected b/test/single_file/basic.c.expected
index 5c2d08e1..a9876be9 100644
--- a/test/single_file/basic.c.expected
+++ b/test/single_file/basic.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/basic.c.noopt.expected b/test/single_file/basic.c.noopt.expected
index 36ccc47f..483c1856 100644
--- a/test/single_file/basic.c.noopt.expected
+++ b/test/single_file/basic.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/binary_long_long_and_long_name_clash.c.noopt.expected b/test/single_file/binary_long_long_and_long_name_clash.c.noopt.expected
index 9801c010..86e31f83 100644
--- a/test/single_file/binary_long_long_and_long_name_clash.c.noopt.expected
+++ b/test/single_file/binary_long_long_and_long_name_clash.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/binary_operands_both_zero.c.expected b/test/single_file/binary_operands_both_zero.c.expected
index 6cc2d25b..49a96b9d 100644
--- a/test/single_file/binary_operands_both_zero.c.expected
+++ b/test/single_file/binary_operands_both_zero.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/binary_operands_both_zero.c.noopt.expected b/test/single_file/binary_operands_both_zero.c.noopt.expected
index 104e4601..3bd1b868 100644
--- a/test/single_file/binary_operands_both_zero.c.noopt.expected
+++ b/test/single_file/binary_operands_both_zero.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/bitfield.c.expected b/test/single_file/bitfield.c.expected
index c7192d14..fe0b8a5f 100644
--- a/test/single_file/bitfield.c.expected
+++ b/test/single_file/bitfield.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/bitfield.c.noopt.expected b/test/single_file/bitfield.c.noopt.expected
index 4e7ffa2b..c32dd3b4 100644
--- a/test/single_file/bitfield.c.noopt.expected
+++ b/test/single_file/bitfield.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/boolean_not_insertion_optimisation.c.expected b/test/single_file/boolean_not_insertion_optimisation.c.expected
index ae2a786c..83305fed 100644
--- a/test/single_file/boolean_not_insertion_optimisation.c.expected
+++ b/test/single_file/boolean_not_insertion_optimisation.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/boolean_not_insertion_optimisation.c.noopt.expected b/test/single_file/boolean_not_insertion_optimisation.c.noopt.expected
index 6b16365f..6f61a9ea 100644
--- a/test/single_file/boolean_not_insertion_optimisation.c.noopt.expected
+++ b/test/single_file/boolean_not_insertion_optimisation.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma.c.expected b/test/single_file/comma.c.expected
index abcc6042..bca6ccea 100644
--- a/test/single_file/comma.c.expected
+++ b/test/single_file/comma.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma.c.noopt.expected b/test/single_file/comma.c.noopt.expected
index f4fd2521..704490da 100644
--- a/test/single_file/comma.c.noopt.expected
+++ b/test/single_file/comma.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma_initialization.c.expected b/test/single_file/comma_initialization.c.expected
index fb60b904..38975073 100644
--- a/test/single_file/comma_initialization.c.expected
+++ b/test/single_file/comma_initialization.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma_initialization.c.noopt.expected b/test/single_file/comma_initialization.c.noopt.expected
index a8785073..b9536fe1 100644
--- a/test/single_file/comma_initialization.c.noopt.expected
+++ b/test/single_file/comma_initialization.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma_side_effects.c.expected b/test/single_file/comma_side_effects.c.expected
index e173663e..0bc6c063 100644
--- a/test/single_file/comma_side_effects.c.expected
+++ b/test/single_file/comma_side_effects.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/comma_side_effects.c.noopt.expected b/test/single_file/comma_side_effects.c.noopt.expected
index 00e5e5e7..0971d762 100644
--- a/test/single_file/comma_side_effects.c.noopt.expected
+++ b/test/single_file/comma_side_effects.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/const_sized_array_int.c.expected b/test/single_file/const_sized_array_int.c.expected
index 9e2ed287..bb477464 100644
--- a/test/single_file/const_sized_array_int.c.expected
+++ b/test/single_file/const_sized_array_int.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/const_sized_array_int.c.noopt.expected b/test/single_file/const_sized_array_int.c.noopt.expected
index d94a4a3b..d1423908 100644
--- a/test/single_file/const_sized_array_int.c.noopt.expected
+++ b/test/single_file/const_sized_array_int.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/define_at_start_of_file.c.expected b/test/single_file/define_at_start_of_file.c.expected
index 04e23ab7..1cb3526a 100644
--- a/test/single_file/define_at_start_of_file.c.expected
+++ b/test/single_file/define_at_start_of_file.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/define_at_start_of_file.c.noopt.expected b/test/single_file/define_at_start_of_file.c.noopt.expected
index 9c3d66ba..0555a667 100644
--- a/test/single_file/define_at_start_of_file.c.noopt.expected
+++ b/test/single_file/define_at_start_of_file.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/define_in_first_decl.c.expected b/test/single_file/define_in_first_decl.c.expected
index 5bef234e..650e4c4b 100644
--- a/test/single_file/define_in_first_decl.c.expected
+++ b/test/single_file/define_in_first_decl.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/define_in_first_decl.c.noopt.expected b/test/single_file/define_in_first_decl.c.noopt.expected
index 94e44b7f..f97bda41 100644
--- a/test/single_file/define_in_first_decl.c.noopt.expected
+++ b/test/single_file/define_in_first_decl.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/do_not_mutate_under_sizeof.c.expected b/test/single_file/do_not_mutate_under_sizeof.c.expected
index 4e673546..04ed0cf5 100644
--- a/test/single_file/do_not_mutate_under_sizeof.c.expected
+++ b/test/single_file/do_not_mutate_under_sizeof.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/do_not_mutate_under_sizeof.c.noopt.expected b/test/single_file/do_not_mutate_under_sizeof.c.noopt.expected
index 814d2feb..a8333db2 100644
--- a/test/single_file/do_not_mutate_under_sizeof.c.noopt.expected
+++ b/test/single_file/do_not_mutate_under_sizeof.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/enum.c.noopt.expected b/test/single_file/enum.c.noopt.expected
index 5923a145..0a94481c 100644
--- a/test/single_file/enum.c.noopt.expected
+++ b/test/single_file/enum.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/expr_lvalue.c.expected b/test/single_file/expr_lvalue.c.expected
index 7ab8b71e..a5c6bdc8 100644
--- a/test/single_file/expr_lvalue.c.expected
+++ b/test/single_file/expr_lvalue.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/expr_lvalue.c.noopt.expected b/test/single_file/expr_lvalue.c.noopt.expected
index d62aefc7..dcd61d11 100644
--- a/test/single_file/expr_lvalue.c.noopt.expected
+++ b/test/single_file/expr_lvalue.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/expr_macro.c.expected b/test/single_file/expr_macro.c.expected
index b6a896e3..aa60e38d 100644
--- a/test/single_file/expr_macro.c.expected
+++ b/test/single_file/expr_macro.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/expr_macro.c.noopt.expected b/test/single_file/expr_macro.c.noopt.expected
index b6a896e3..aa60e38d 100644
--- a/test/single_file/expr_macro.c.noopt.expected
+++ b/test/single_file/expr_macro.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/float_binary_opts.c.expected b/test/single_file/float_binary_opts.c.expected
index 1c305701..36abbe72 100644
--- a/test/single_file/float_binary_opts.c.expected
+++ b/test/single_file/float_binary_opts.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/float_binary_opts.c.noopt.expected b/test/single_file/float_binary_opts.c.noopt.expected
index 1ffe53da..df32292d 100644
--- a/test/single_file/float_binary_opts.c.noopt.expected
+++ b/test/single_file/float_binary_opts.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/float_unary_opt.c.expected b/test/single_file/float_unary_opt.c.expected
index dd3c39ca..dba76b22 100644
--- a/test/single_file/float_unary_opt.c.expected
+++ b/test/single_file/float_unary_opt.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/float_unary_opt.c.noopt.expected b/test/single_file/float_unary_opt.c.noopt.expected
index 2d472377..d591162c 100644
--- a/test/single_file/float_unary_opt.c.noopt.expected
+++ b/test/single_file/float_unary_opt.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/floats.c.expected b/test/single_file/floats.c.expected
index 7a8fa5ab..d0f137c5 100644
--- a/test/single_file/floats.c.expected
+++ b/test/single_file/floats.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/floats.c.noopt.expected b/test/single_file/floats.c.noopt.expected
index 677a4af1..5e05b8ef 100644
--- a/test/single_file/floats.c.noopt.expected
+++ b/test/single_file/floats.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/initializer.c.expected b/test/single_file/initializer.c.expected
index 0d442e1c..286fe181 100644
--- a/test/single_file/initializer.c.expected
+++ b/test/single_file/initializer.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/initializer.c.noopt.expected b/test/single_file/initializer.c.noopt.expected
index 0d442e1c..286fe181 100644
--- a/test/single_file/initializer.c.noopt.expected
+++ b/test/single_file/initializer.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/large_summation.c.expected b/test/single_file/large_summation.c.expected
index 43083795..d5a8648c 100644
--- a/test/single_file/large_summation.c.expected
+++ b/test/single_file/large_summation.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/large_summation.c.noopt.expected b/test/single_file/large_summation.c.noopt.expected
index 43083795..d5a8648c 100644
--- a/test/single_file/large_summation.c.noopt.expected
+++ b/test/single_file/large_summation.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/left_shift_opt.c.expected b/test/single_file/left_shift_opt.c.expected
index a516dc59..fec80470 100644
--- a/test/single_file/left_shift_opt.c.expected
+++ b/test/single_file/left_shift_opt.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/left_shift_opt.c.noopt.expected b/test/single_file/left_shift_opt.c.noopt.expected
index 88b79c83..97d66911 100644
--- a/test/single_file/left_shift_opt.c.noopt.expected
+++ b/test/single_file/left_shift_opt.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/logical_and.c.expected b/test/single_file/logical_and.c.expected
index 953bf122..0f17202d 100644
--- a/test/single_file/logical_and.c.expected
+++ b/test/single_file/logical_and.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/logical_and.c.noopt.expected b/test/single_file/logical_and.c.noopt.expected
index 953bf122..0f17202d 100644
--- a/test/single_file/logical_and.c.noopt.expected
+++ b/test/single_file/logical_and.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/logical_or.c.expected b/test/single_file/logical_or.c.expected
index d087ddea..6d3d96be 100644
--- a/test/single_file/logical_or.c.expected
+++ b/test/single_file/logical_or.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/logical_or.c.noopt.expected b/test/single_file/logical_or.c.noopt.expected
index d087ddea..6d3d96be 100644
--- a/test/single_file/logical_or.c.noopt.expected
+++ b/test/single_file/logical_or.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/macro_pasting.c.expected b/test/single_file/macro_pasting.c.expected
index a2f5fa61..bb12b6d6 100644
--- a/test/single_file/macro_pasting.c.expected
+++ b/test/single_file/macro_pasting.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/macro_pasting.c.noopt.expected b/test/single_file/macro_pasting.c.noopt.expected
index 99c134f2..38ac36c0 100644
--- a/test/single_file/macro_pasting.c.noopt.expected
+++ b/test/single_file/macro_pasting.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/negative_switch_case.c.expected b/test/single_file/negative_switch_case.c.expected
index 88585c07..07a15f7e 100644
--- a/test/single_file/negative_switch_case.c.expected
+++ b/test/single_file/negative_switch_case.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/negative_switch_case.c.noopt.expected b/test/single_file/negative_switch_case.c.noopt.expected
index 633783bf..cc3dac55 100644
--- a/test/single_file/negative_switch_case.c.noopt.expected
+++ b/test/single_file/negative_switch_case.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/non_const_sized_array.c.expected b/test/single_file/non_const_sized_array.c.expected
index 369ffa15..c7b69fd6 100644
--- a/test/single_file/non_const_sized_array.c.expected
+++ b/test/single_file/non_const_sized_array.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/non_const_sized_array.c.noopt.expected b/test/single_file/non_const_sized_array.c.noopt.expected
index 3965a159..809e1bce 100644
--- a/test/single_file/non_const_sized_array.c.noopt.expected
+++ b/test/single_file/non_const_sized_array.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/positive_int_as_minus_one.c.expected b/test/single_file/positive_int_as_minus_one.c.expected
index 89e86ca4..cc0fb695 100644
--- a/test/single_file/positive_int_as_minus_one.c.expected
+++ b/test/single_file/positive_int_as_minus_one.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/positive_int_as_minus_one.c.noopt.expected b/test/single_file/positive_int_as_minus_one.c.noopt.expected
index 3474c309..c77f2c9d 100644
--- a/test/single_file/positive_int_as_minus_one.c.noopt.expected
+++ b/test/single_file/positive_int_as_minus_one.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/post_inc_volatile.c.expected b/test/single_file/post_inc_volatile.c.expected
index c93b96f7..707784dc 100644
--- a/test/single_file/post_inc_volatile.c.expected
+++ b/test/single_file/post_inc_volatile.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/post_inc_volatile.c.noopt.expected b/test/single_file/post_inc_volatile.c.noopt.expected
index 924efe2d..1dc4b860 100644
--- a/test/single_file/post_inc_volatile.c.noopt.expected
+++ b/test/single_file/post_inc_volatile.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/preprocessor_if.c.expected b/test/single_file/preprocessor_if.c.expected
index 84b9edc4..63e7af23 100644
--- a/test/single_file/preprocessor_if.c.expected
+++ b/test/single_file/preprocessor_if.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/preprocessor_if.c.noopt.expected b/test/single_file/preprocessor_if.c.noopt.expected
index 51ba04f1..79db936f 100644
--- a/test/single_file/preprocessor_if.c.noopt.expected
+++ b/test/single_file/preprocessor_if.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/printing.c.expected b/test/single_file/printing.c.expected
index 149a7870..4bc51c02 100644
--- a/test/single_file/printing.c.expected
+++ b/test/single_file/printing.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/printing.c.noopt.expected b/test/single_file/printing.c.noopt.expected
index e4ee745a..14b0b713 100644
--- a/test/single_file/printing.c.noopt.expected
+++ b/test/single_file/printing.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/space_needed_after_macro.c.expected b/test/single_file/space_needed_after_macro.c.expected
index 34de312f..0a34e868 100644
--- a/test/single_file/space_needed_after_macro.c.expected
+++ b/test/single_file/space_needed_after_macro.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/space_needed_after_macro.c.noopt.expected b/test/single_file/space_needed_after_macro.c.noopt.expected
index 0f354852..05aec664 100644
--- a/test/single_file/space_needed_after_macro.c.noopt.expected
+++ b/test/single_file/space_needed_after_macro.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/space_needed_after_macro2.c.expected b/test/single_file/space_needed_after_macro2.c.expected
index e3ec8694..d1934771 100644
--- a/test/single_file/space_needed_after_macro2.c.expected
+++ b/test/single_file/space_needed_after_macro2.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/space_needed_after_macro2.c.noopt.expected b/test/single_file/space_needed_after_macro2.c.noopt.expected
index a6a1d2f8..69b8c98e 100644
--- a/test/single_file/space_needed_after_macro2.c.noopt.expected
+++ b/test/single_file/space_needed_after_macro2.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/switch_cases1.c.expected b/test/single_file/switch_cases1.c.expected
index 113b8542..90c4e05e 100644
--- a/test/single_file/switch_cases1.c.expected
+++ b/test/single_file/switch_cases1.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/switch_cases1.c.noopt.expected b/test/single_file/switch_cases1.c.noopt.expected
index fd7ca5b4..39d0d418 100644
--- a/test/single_file/switch_cases1.c.noopt.expected
+++ b/test/single_file/switch_cases1.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/switch_cases2.c.expected b/test/single_file/switch_cases2.c.expected
index bcc308e4..e9ac4f06 100644
--- a/test/single_file/switch_cases2.c.expected
+++ b/test/single_file/switch_cases2.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/switch_cases2.c.noopt.expected b/test/single_file/switch_cases2.c.noopt.expected
index 64004b4b..81d009bc 100644
--- a/test/single_file/switch_cases2.c.noopt.expected
+++ b/test/single_file/switch_cases2.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/typedef.c.noopt.expected b/test/single_file/typedef.c.noopt.expected
index 43f8ca46..71322608 100644
--- a/test/single_file/typedef.c.noopt.expected
+++ b/test/single_file/typedef.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary.c.expected b/test/single_file/unary.c.expected
index 2541a4d9..ab22d655 100644
--- a/test/single_file/unary.c.expected
+++ b/test/single_file/unary.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary.c.noopt.expected b/test/single_file/unary.c.noopt.expected
index f1e67bfd..94deab8d 100644
--- a/test/single_file/unary.c.noopt.expected
+++ b/test/single_file/unary.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_logical_not.c.expected b/test/single_file/unary_logical_not.c.expected
index 17c5dc41..8344c43c 100644
--- a/test/single_file/unary_logical_not.c.expected
+++ b/test/single_file/unary_logical_not.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_logical_not.c.noopt.expected b/test/single_file/unary_logical_not.c.noopt.expected
index d9c000f9..e7b24a19 100644
--- a/test/single_file/unary_logical_not.c.noopt.expected
+++ b/test/single_file/unary_logical_not.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_minus.c.expected b/test/single_file/unary_minus.c.expected
index 091a1d64..12f5fcb6 100644
--- a/test/single_file/unary_minus.c.expected
+++ b/test/single_file/unary_minus.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_minus.c.noopt.expected b/test/single_file/unary_minus.c.noopt.expected
index 8e9362eb..e027d419 100644
--- a/test/single_file/unary_minus.c.noopt.expected
+++ b/test/single_file/unary_minus.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_operator_opt.c.expected b/test/single_file/unary_operator_opt.c.expected
index 562605a1..f48bd94b 100644
--- a/test/single_file/unary_operator_opt.c.expected
+++ b/test/single_file/unary_operator_opt.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unary_operator_opt.c.noopt.expected b/test/single_file/unary_operator_opt.c.noopt.expected
index c0494c56..b4e8ab3b 100644
--- a/test/single_file/unary_operator_opt.c.noopt.expected
+++ b/test/single_file/unary_operator_opt.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unsigned_int.c.expected b/test/single_file/unsigned_int.c.expected
index 319724d2..4015472d 100644
--- a/test/single_file/unsigned_int.c.expected
+++ b/test/single_file/unsigned_int.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/unsigned_int.c.noopt.expected b/test/single_file/unsigned_int.c.noopt.expected
index f0593c38..bf5a13ae 100644
--- a/test/single_file/unsigned_int.c.noopt.expected
+++ b/test/single_file/unsigned_int.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/volatile.c.expected b/test/single_file/volatile.c.expected
index a1012ad3..a0fec408 100644
--- a/test/single_file/volatile.c.expected
+++ b/test/single_file/volatile.c.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;
diff --git a/test/single_file/volatile.c.noopt.expected b/test/single_file/volatile.c.noopt.expected
index 0e614c41..59fb66f9 100644
--- a/test/single_file/volatile.c.noopt.expected
+++ b/test/single_file/volatile.c.noopt.expected
@@ -17,7 +17,7 @@
 #elif __APPLE__
 #define thread_local __thread
 #else
-#include <threads.h>
+#define thread_local _Thread_local
 #endif
 
 static thread_local int __dredd_some_mutation_enabled = 1;