diff -ur fex/fex/blargg_common.h fex/fex/blargg_common.h
--- fex/fex/blargg_common.h	2017-12-11 04:23:06.117064206 +0200
+++ fex/fex/blargg_common.h	2017-12-11 04:24:33.193846532 +0200
@@ -12,7 +12,7 @@
 typedef const char* blargg_err_t; // 0 on success, otherwise error string
 
 // Success; no error
-int const blargg_ok = 0;
+static const char* blargg_ok = 0;
 
 // BLARGG_RESTRICT: equivalent to C99's restrict, where supported
 #if __GNUC__ >= 3 || _MSC_VER >= 1100
