diff --git a/xpcom/tests/TestUnicodeArguments.cpp b/xpcom/tests/TestUnicodeArguments.cpp
index 90947c3acfe0..35d80a7f4394 100644
--- a/xpcom/tests/TestUnicodeArguments.cpp
+++ b/xpcom/tests/TestUnicodeArguments.cpp
@@ -4,7 +4,7 @@
  */
 
 static const int args_length = 4;
-#ifdef XP_WIN
+#if defined(XP_WIN) && defined(_MSC_VER)
 #define _UNICODE
 #include <tchar.h>
 #include <stdio.h>