diff --git a/src/include/nacl_compiler_annotations.h b/src/include/nacl_compiler_annotations.h
index c9baad67b7..b8e46d2f26 100644
--- a/src/include/nacl_compiler_annotations.h
+++ b/src/include/nacl_compiler_annotations.h
@@ -10,7 +10,7 @@
 #include "native_client/src/include/build_config.h"
 
 /* MSVC supports "inline" only in C++ */
-#if NACL_WINDOWS
+#if defined(_MSC_VER)
 # define INLINE __forceinline
 #else
 # define INLINE __inline__
diff --git a/src/include/portability.h b/src/include/portability.h
index d0360ebfa9..42aab4d5a5 100644
--- a/src/include/portability.h
+++ b/src/include/portability.h
@@ -16,6 +16,7 @@
 #ifndef NATIVE_CLIENT_SRC_INCLUDE_PORTABILITY_H_
 #define NATIVE_CLIENT_SRC_INCLUDE_PORTABILITY_H_ 1
 
+#include <stdint.h>
 #include <stdlib.h>
 
 #include "native_client/src/include/build_config.h"
@@ -30,7 +31,9 @@
 
 #if NACL_WINDOWS
 /* disable warnings for deprecated functions like getenv, etc. */
+#if defined(_MSC_VER)
 #pragma warning(disable : 4996)
+#endif
 # include <malloc.h>
 /* TODO: eliminate port_win.h */
 # include "native_client/src/include/win/port_win.h"
@@ -59,7 +62,7 @@
 #define GG_UINT32_C(x)  (x ## U)
 #define GG_UINT64_C(x)  GG_ULONGLONG(x)
 
-#if NACL_WINDOWS
+#if NACL_WINDOWS && defined(_MSC_VER)
 #define GG_LONGLONG(x) x##I64
 #define GG_ULONGLONG(x) x##UI64
 #else
diff --git a/src/include/portability_io.h b/src/include/portability_io.h
index 75eedbf12d..8abafd023f 100644
--- a/src/include/portability_io.h
+++ b/src/include/portability_io.h
@@ -17,7 +17,9 @@
 
 #if NACL_WINDOWS
 /* disable warnings for deprecated _snprintf */
+#if defined(_MSC_VER)
 #pragma warning(disable : 4996)
+#endif
 
 #include <io.h>
 #include <direct.h>
@@ -43,7 +45,9 @@
 /* missing from win stdio.h and fcntl.h */
 
 /* from bits/fcntl.h */
+#if defined(_MSC_VER)
 #define O_ACCMODE 0003
+#endif
 
 #else
 
diff --git a/src/include/portability_string.h b/src/include/portability_string.h
index 9b86ead994..1c49954770 100644
--- a/src/include/portability_string.h
+++ b/src/include/portability_string.h
@@ -53,7 +53,9 @@ size_t strnlen(const char* str, size_t max);
 
 #if NACL_WINDOWS
 /* disable warnings for deprecated strncpy */
+#if defined(_MSC_VER)
 #pragma warning(disable : 4996)
+#endif
 
 #define STRDUP _strdup
 #define STRTOLL _strtoi64
diff --git a/src/include/win/port_win.h b/src/include/win/port_win.h
index 790a8fe3e8..8130db69c2 100644
--- a/src/include/win/port_win.h
+++ b/src/include/win/port_win.h
@@ -38,6 +38,7 @@
 
 /* TODO: eliminated this file and move its contents to portability*.h */
 
+#if defined(_MSC_VER)
 /* wchar_t and unsigned short are not always equivalent*/
 #pragma warning(disable : 4255)
 /* padding added after struct member */
@@ -46,6 +47,7 @@
 #pragma warning(disable: 4826)
 /* conditional expression is constant */
 #pragma warning(disable : 4127)
+#endif
 
 /* TODO: limit this include to files that really need it */
 #ifndef NOMINMAX
@@ -74,7 +76,9 @@ typedef __int64_t         int64_t;
 typedef __uint64_t        uint64_t;
 
 typedef long              off_t;
+#if defined(_MSC_VER)
 typedef int               mode_t;
+#endif
 typedef long              _off_t;
 typedef long int          __loff_t;
 typedef unsigned long     DWORD;
@@ -94,7 +98,7 @@ typedef int32_t           ssize_t;
  *
  * Only including range values actually used in our codebase.
  */
-#if _MSC_VER >= 1800
+#if !defined(_MSC_VER) || _MSC_VER >= 1800
 #include <stdint.h>
 #else
 # if !defined(UINT8_MAX)
@@ -160,6 +164,8 @@ EXTERN_C_END
 
 
 /* from linux/limits.h, via sys/param.h */
+#if defined(_MSC_VER)
 #define PATH_MAX 4096
+#endif
 
 #endif  /* NATIVE_CLIENT_SRC_INCLUDE_WIN_PORT_WIN_H_ */
diff --git a/src/shared/platform/win/lock_impl.h b/src/shared/platform/win/lock_impl.h
index cb5f98b8d3..9024ea3a06 100644
--- a/src/shared/platform/win/lock_impl.h
+++ b/src/shared/platform/win/lock_impl.h
@@ -8,7 +8,7 @@
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_PLATFORM_WIN_LOCK_IMPL_H_
 #define NATIVE_CLIENT_SRC_TRUSTED_PLATFORM_WIN_LOCK_IMPL_H_
 
-#include <Windows.h>
+#include <windows.h>
 #include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/shared/platform/nacl_sync.h"
 
diff --git a/src/shared/platform/win/nacl_exit.c b/src/shared/platform/win/nacl_exit.c
index a190175ff5..17c7741d89 100644
--- a/src/shared/platform/win/nacl_exit.c
+++ b/src/shared/platform/win/nacl_exit.c
@@ -39,7 +39,11 @@ void NaClAbort(void) {
    * http://code.google.com/p/nativeclient/issues/detail?id=2772).
    */
   while (1) {
+#if defined(_MSC_VER)
     __halt();
+#else
+    __asm__("hlt");
+#endif
   }
 }
 
diff --git a/src/shared/platform/win/port_win.c b/src/shared/platform/win/port_win.c
index 2f303ff10a..d743bd1c49 100644
--- a/src/shared/platform/win/port_win.c
+++ b/src/shared/platform/win/port_win.c
@@ -12,7 +12,7 @@
 
 #include "native_client/src/include/portability.h"
 
-#if ( DO_NOT_USE_FAST_ASSEMBLER_VERSION_FOR_FFS || defined(_WIN64) )
+#if ( DO_NOT_USE_FAST_ASSEMBLER_VERSION_FOR_FFS || defined(_WIN64) || !defined(_MSC_VER) )
 int ffs(int x) {
   int r = 1;
 
diff --git a/src/shared/platform/win/xlate_system_error.c b/src/shared/platform/win/xlate_system_error.c
index cfaca7c266..b9d51f34fd 100644
--- a/src/shared/platform/win/xlate_system_error.c
+++ b/src/shared/platform/win/xlate_system_error.c
@@ -9,7 +9,7 @@
  */
 
 #include <errno.h>
-#include <WinError.h>
+#include <winerror.h>
 
 #include "native_client/src/shared/platform/nacl_log.h"
 #include "native_client/src/shared/platform/win/xlate_system_error.h"
diff --git a/src/trusted/fault_injection/fault_injection.c b/src/trusted/fault_injection/fault_injection.c
index 3d71f5f7b2..2fa29c35d9 100644
--- a/src/trusted/fault_injection/fault_injection.c
+++ b/src/trusted/fault_injection/fault_injection.c
@@ -66,6 +66,8 @@
  */
 # define NACL_HAS_STRNDUP   0
 /* could use TLS if not built into a DLL, otherwise must use TLSALLOC */
+# define NACL_USE_TLS       0
+# define NACL_USE_TSD       0
 # define NACL_USE_TLSALLOC  1
 # include <windows.h>
 #endif
diff --git a/src/trusted/service_runtime/arch/x86_32/sel_rt_32.c b/src/trusted/service_runtime/arch/x86_32/sel_rt_32.c
index 5757b6c904..15d543639e 100644
--- a/src/trusted/service_runtime/arch/x86_32/sel_rt_32.c
+++ b/src/trusted/service_runtime/arch/x86_32/sel_rt_32.c
@@ -90,7 +90,7 @@ int NaClAppThreadInitArchSpecific(struct NaClAppThread *natp,
    * Save the system's state of the x87 FPU control word so we can restore
    * the same state when returning to trusted code.
    */
-#if NACL_WINDOWS
+#if defined(_MSC_VER)
   {
     uint16_t sys_fcw;
     __asm {
diff --git a/src/trusted/service_runtime/nacl_signal.h b/src/trusted/service_runtime/nacl_signal.h
index e3a8fa1732..2301ed407e 100644
--- a/src/trusted/service_runtime/nacl_signal.h
+++ b/src/trusted/service_runtime/nacl_signal.h
@@ -58,7 +58,7 @@ struct NaClExceptionFrame;
 #define NACL_ABI_WIFSIGNALED(status) ((((status) + 1) & 0x7f) > 1)
 #define NACL_ABI_W_EXITCODE(ret, sig) ((((ret) & 0xff) << 8) + ((sig) & 0x7f))
 
-#if NACL_WINDOWS
+#if NACL_WINDOWS && defined(_MSC_VER)
 enum PosixSignals {
   SIGINT  = 2,
   SIGQUIT = 3,
diff --git a/src/trusted/service_runtime/sel_ldr.c b/src/trusted/service_runtime/sel_ldr.c
index 4dbc7611cb..7bcf97c210 100644
--- a/src/trusted/service_runtime/sel_ldr.c
+++ b/src/trusted/service_runtime/sel_ldr.c
@@ -912,7 +912,7 @@ void NaClVmIoPendingCheck_mu(struct NaClApp *nap,
  * We need its symbol in the symbol table so don't inline it.
  * TODO(dje): add some explanation for the non-GDB person.
  */
-#if NACL_WINDOWS
+#if NACL_WINDOWS && defined(_MSVC_VER)
 __declspec(dllexport noinline)
 #endif
 #ifdef __GNUC__
diff --git a/src/trusted/validator/validation_cache.c b/src/trusted/validator/validation_cache.c
index b9d9536bb7..f8ce53e9ef 100644
--- a/src/trusted/validator/validation_cache.c
+++ b/src/trusted/validator/validation_cache.c
@@ -21,7 +21,7 @@
 #include "native_client/src/trusted/validator/validation_metadata.h"
 
 #if NACL_WINDOWS
-#include <Windows.h>
+#include <windows.h>
 #include <io.h>
 #endif
 
diff --git a/src/trusted/validator_ragel/bitmap.h b/src/trusted/validator_ragel/bitmap.h
index dec2a0d2cb..798e392b72 100644
--- a/src/trusted/validator_ragel/bitmap.h
+++ b/src/trusted/validator_ragel/bitmap.h
@@ -15,7 +15,7 @@
 #include "native_client/src/include/nacl_macros.h"
 #include "native_client/src/include/portability.h"
 
-#if NACL_WINDOWS
+#if defined(_MSC_VER)
 # define FORCEINLINE __forceinline
 #else
 # define FORCEINLINE __inline __attribute__ ((always_inline))
diff --git a/src/trusted/validator_ragel/decoding.h b/src/trusted/validator_ragel/decoding.h
index 64087b7621..51a781d14e 100644
--- a/src/trusted/validator_ragel/decoding.h
+++ b/src/trusted/validator_ragel/decoding.h
@@ -19,7 +19,7 @@
 #include "native_client/src/include/build_config.h"
 #include "native_client/src/trusted/validator_ragel/decoder.h"
 
-#if NACL_WINDOWS
+#if defined(_MSC_VER)
 # define FORCEINLINE __forceinline
 #else
 # define FORCEINLINE __inline __attribute__ ((always_inline))