--- a/ext_src/yocto/ext/filesystem.hpp
+++ b/ext_src/yocto/ext/filesystem.hpp
@@ -1531,8 +1531,8 @@
     return rc == 0 ? (const char*)buffer : "Error in strerror_r!";
 #else
     char buffer[512];
-    char* msg = strerror_r(code ? code : errno, buffer, sizeof(buffer));
-    return msg ? msg : buffer;
+    int msg = strerror_r(code ? code : errno, buffer, sizeof(buffer));
+    return msg == 0 ? (const char*)buffer : "Error in strerror_r!";
 #endif
 }