diff --git a/build_win_dbg.sh b/build_win_dbg.sh
index 7311921a..f730d590 100755
--- a/build_win_dbg.sh
+++ b/build_win_dbg.sh
@@ -2,8 +2,8 @@
 
 # NOTE: -gdwarf-2 needed for my version of wine to recognize the symbols.
 
-x86_64-w64-mingw32-gcc -Wall -W -Werror \
-    -g -gdwarf-2 -o beebjit.exe \
+x86_64-w64-mingw32-gcc -Wall -W -Werror -Wno-error=address-of-packed-member \
+    -D__MSVCRT_VERSION__=0x1300 -g -gdwarf-2 -o beebjit.exe \
     main.c config.c bbc.c defs_6502.c state.c video.c via.c \
     emit_6502.c interp.c inturbo.c state_6502.c sound.c timing.c \
     jit_compiler.c cpu_driver.c \
diff --git a/build_win_opt.sh b/build_win_opt.sh
index 0b81e091..c3aebca3 100755
--- a/build_win_opt.sh
+++ b/build_win_opt.sh
@@ -2,8 +2,8 @@
 
 # NOTE: -gdwarf-2 needed for my version of wine to recognize the symbols.
 
-x86_64-w64-mingw32-gcc -Wall -W -Werror \
-    -O3 -DNDEBUG -o beebjit.exe \
+x86_64-w64-mingw32-gcc -Wall -W -Werror -Wno-error=address-of-packed-member \
+    -O3 -DNDEBUG -D__MSVCRT_VERSION__=0x1300 -o beebjit.exe \
     main.c config.c bbc.c defs_6502.c state.c video.c via.c \
     emit_6502.c interp.c inturbo.c state_6502.c sound.c timing.c \
     jit_compiler.c cpu_driver.c \
diff --git a/main.c b/main.c
index 35e39a67..e4ea4ee8 100644
--- a/main.c
+++ b/main.c
@@ -4,6 +4,7 @@
 #include "keyboard.h"
 #include "log.h"
 #include "os_channel.h"
+#include "os_file.h"
 #include "os_poller.h"
 #include "os_sound.h"
 #include "os_terminal.h"
@@ -59,7 +60,6 @@ main_save_frame(const char* p_frames_dir,
 int
 main(int argc, const char* argv[]) {
   int i_args;
-  size_t read_ret;
   uint8_t os_rom[k_bbc_rom_size];
   uint8_t load_rom[k_bbc_rom_size];
   uint32_t i;
@@ -129,10 +129,14 @@ main(int argc, const char* argv[]) {
   uint64_t frame_cycles = 0;
   uint32_t max_frames = 1;
   int is_exit_on_max_frames_flag = 0;
+  char* executable_path = NULL;
+  char* rom_full_name = NULL;
 
   p_opt_flags = util_mallocz(1);
   p_log_flags = util_mallocz(1);
 
+  executable_path = os_file_get_executable_path();
+
   for (i_args = 1; i_args < argc; ++i_args) {
     const char* arg = argv[i_args];
     int has_1 = 0;
@@ -372,10 +376,12 @@ main(int argc, const char* argv[]) {
   (void) memset(os_rom, '\0', k_bbc_rom_size);
   (void) memset(load_rom, '\0', k_bbc_rom_size);
 
-  read_ret = util_file_read_fully(os_rom_name, os_rom, k_bbc_rom_size);
-  if (read_ret != k_bbc_rom_size) {
+  rom_full_name = util_file_name_join(executable_path, os_rom_name);
+  if (util_file_read_fully(rom_full_name, os_rom, k_bbc_rom_size) != k_bbc_rom_size) {
     util_bail("can't load OS rom");
   }
+  util_free(rom_full_name);
+  rom_full_name = NULL;
 
   if (terminal_flag) {
     /* If we're in terminal mode and it appears to be an OS v1.2 MOS ROM,
@@ -465,7 +471,10 @@ main(int argc, const char* argv[]) {
     const char* p_rom_name = rom_names[i];
     if (p_rom_name != NULL) {
       (void) memset(load_rom, '\0', k_bbc_rom_size);
-      (void) util_file_read_fully(p_rom_name, load_rom, k_bbc_rom_size);
+	  rom_full_name = util_file_name_join(executable_path, p_rom_name);
+      (void) util_file_read_fully(rom_full_name, load_rom, k_bbc_rom_size);
+	  util_free(rom_full_name);
+	  rom_full_name = NULL;
       bbc_load_rom(p_bbc, i, load_rom);
     }
     if (sideways_ram[i]) {
@@ -473,6 +482,9 @@ main(int argc, const char* argv[]) {
     }
   }
 
+  util_free(executable_path);
+  executable_path = NULL;
+
   if (load_name != NULL) {
     state_load(p_bbc, load_name);
   }
diff --git a/os.c b/os.c
index c10d9a33..f076a521 100644
--- a/os.c
+++ b/os.c
@@ -6,6 +6,7 @@
 #include "os_alloc_posix.c"
 #include "os_channel_posix.c"
 #include "os_fault_posix.c"
+#include "os_file_posix.c"
 #include "os_poller_posix.c"
 #include "os_terminal_posix.c"
 #include "os_thread_linux.c"
@@ -29,6 +30,7 @@
 #include "os_alloc_windows.c"
 #include "os_channel_windows.c"
 #include "os_fault_windows.c"
+#include "os_file_windows.c"
 #include "os_poller_windows.c"
 #include "os_sound_windows.c"
 #include "os_terminal_windows.c"
diff --git a/os_file.h b/os_file.h
new file mode 100644
index 00000000..57c7a64f
--- /dev/null
+++ b/os_file.h
@@ -0,0 +1,9 @@
+#ifndef BEEBJIT_OS_FILE_H
+#define BEEBJIT_OS_FILE_H
+
+#include <stdint.h>
+
+char* os_file_get_executable_path(void);
+char os_file_get_separator_char(void);
+
+#endif /* BEEBJIT_OS_FILE_H */
diff --git a/os_file_posix.c b/os_file_posix.c
new file mode 100644
index 00000000..3afc8de4
--- /dev/null
+++ b/os_file_posix.c
@@ -0,0 +1,12 @@
+#include "os_file.h"
+
+
+char*
+os_file_get_executable_path(void) {
+  return NULL;
+}
+
+char
+os_file_get_separator_char(void) {
+	return '/';
+}
diff --git a/os_file_windows.c b/os_file_windows.c
new file mode 100644
index 00000000..4acdbef5
--- /dev/null
+++ b/os_file_windows.c
@@ -0,0 +1,25 @@
+#include "os_file.h"
+#include <windows.h>
+
+
+char*
+os_file_get_executable_path(void) {
+  char* executable_path = util_malloc(MAX_PATH);
+  if (GetModuleFileNameA(NULL, executable_path, MAX_PATH) < MAX_PATH) {
+    char* path_leaf = strrchr(executable_path, '\\');
+    if (path_leaf) {
+      *path_leaf = 0;
+    } else {
+      *executable_path = 0;
+	}
+  } else {
+    util_bail("Could not get Win32 executable path");
+  }
+
+  return executable_path;
+}
+
+char
+os_file_get_separator_char(void) {
+	return '\\';
+}
diff --git a/util.c b/util.c
index 46d5312f..3f59bcda 100644
--- a/util.c
+++ b/util.c
@@ -1,4 +1,5 @@
 #include "util.h"
+#include "os_file.h"
 
 #include <assert.h>
 #include <ctype.h>
@@ -58,7 +59,7 @@ util_strdup2(const char* p_str1, const char* p_str2) {
     util_bail("integer overflow");
   }
 
-  p_ret = malloc(len + 1);
+  p_ret = util_malloc(len + 1);
   (void) memcpy(p_ret, p_str1, len1);
   (void) memcpy((p_ret + len1), p_str2, len2);
   p_ret[len] = '\0';
@@ -66,6 +67,19 @@ util_strdup2(const char* p_str1, const char* p_str2) {
   return p_ret;
 }
 
+char*
+util_strndup(const char *s, size_t n) {
+    char *p;
+    size_t n1;
+
+    for (n1 = 0; n1 < n && s[n1] != '\0'; n1++)
+        continue;
+    p = util_malloc(n1 + 1);
+    memcpy(p, s, n1);
+    p[n1] = '\0';
+    return p;
+}
+
 struct util_buffer {
   uint8_t* p_mem;
   size_t length;
@@ -269,10 +283,10 @@ util_file_name_split(char** p_file_name_base,
   size_t len;
   const char* p_sep = NULL;
   const char* p_str = p_full_file_name;
+  char separator_char = os_file_get_separator_char();
 
-  /* TODO: respect Windows separator? */
   while (*p_str != '\0') {
-    if (*p_str == '/') {
+    if (*p_str == separator_char) {
       p_sep = p_str;
     }
     p_str++;
@@ -284,7 +298,7 @@ util_file_name_split(char** p_file_name_base,
   }
 
   len = (p_sep - p_full_file_name);
-  *p_file_name_base = strndup(p_full_file_name, len);
+  *p_file_name_base = util_strndup(p_full_file_name, len);
   *p_file_name = strdup(p_sep + 1);
 }
 
@@ -296,11 +310,11 @@ util_file_name_join(const char* p_file_name_base, const char* p_file_name) {
     return strdup(p_file_name);
   }
 
-  /* TODO: respect Windows separator? */
   (void) snprintf(file_name_buf,
                   sizeof(file_name_buf),
-                  "%s/%s",
+                  "%s%c%s",
                   p_file_name_base,
+                  os_file_get_separator_char(),
                   p_file_name);
   return strdup(&file_name_buf[0]);
 }
diff --git a/util.h b/util.h
index 6bfa7c61..7bd3382f 100644
--- a/util.h
+++ b/util.h
@@ -10,6 +10,7 @@ void* util_mallocz(size_t size);
 void util_free(void* p);
 char* util_strdup(const char* p_str);
 char* util_strdup2(const char* p_str1, const char* p_str2);
+char* util_strndup(const char *s, size_t n);
 
 /* Buffer. */
 struct util_buffer;