diff --git a/src/functionloading.jl b/src/functionloading.jl
index 74e9e73..24e7d4e 100644
--- a/src/functionloading.jl
+++ b/src/functionloading.jl
@@ -33,6 +33,10 @@ function debug_opengl_expr(func_name, args)
     end
 end
 
+# On 32-bit Windows, OpenGL functions use stdcall calling convention (APIENTRY).
+# On 64-bit Windows (and all other platforms), there is only one calling convention.
+const _gl_calling_convention = (Sys.iswindows() && Sys.WORD_SIZE == 32) ? :stdcall : :cdecl
+
 # based on getCFun macro
 macro glfunc(opengl_func)
     arguments = map(opengl_func.args[1].args[2:end]) do arg
@@ -47,6 +51,7 @@ macro glfunc(opengl_func)
     func_name_sym   = Expr(:quote, func_name)
     func_name_str   = string(func_name)
     ptr_expr        = :(getprocaddress_e($func_name_str))
+    cc              = _gl_calling_convention
 
     if Sys.iswindows() # windows has some function pointers statically available and some not, this is how we deal with it:
         ptr = Libdl.dlsym_e(gl_lib, func_name)
@@ -54,7 +59,7 @@ macro glfunc(opengl_func)
             ptr_expr = :(($func_name_sym, "opengl32"))
             ret = quote
                 function $func_name($(arg_names...))
-                    result = ccall($ptr_expr, $return_type, ($(input_types...),), $(arg_names...))
+                    result = ccall($ptr_expr, $(cc), $return_type, ($(input_types...),), $(arg_names...))
                     $(debug_opengl_expr(func_name, arg_names))
                     result
                 end
@@ -70,7 +75,7 @@ macro glfunc(opengl_func)
             if $ptr_sym[]::Ptr{Cvoid} == C_NULL
                 $ptr_sym[]::Ptr{Cvoid} = $ptr_expr
             end
-            result = ccall($ptr_sym[]::Ptr{Cvoid}, $return_type, ($(input_types...),), $(arg_names...))
+            result = ccall($ptr_sym[]::Ptr{Cvoid}, $(cc), $return_type, ($(input_types...),), $(arg_names...))
             $(debug_opengl_expr(func_name, arg_names))
             result
         end