diff --git a/ext/ruby_debug/ruby_debug.c b/ext/ruby_debug/ruby_debug.c
index 378c44f..a4d314d 100644
--- a/ext/ruby_debug/ruby_debug.c
+++ b/ext/ruby_debug/ruby_debug.c
@@ -521,9 +521,9 @@ filename_cmp_impl(VALUE source, char *file);
 
 int
 filename_cmp(VALUE source, char *file) {
-#ifdef __WIN32__
+#ifdef _WIN32
     return filename_cmp_impl(source, file);
-#endif
+#else
 
     if (!RTEST(resolve_symlinks)) {
         return filename_cmp_impl(source, file);
@@ -547,6 +547,7 @@ filename_cmp(VALUE source, char *file) {
       return result;
     }
 #endif  
+#endif  
 }
 
 int