diff --git a/src/log.h b/src/log.h
index b1fae24..64dccd7 100644
--- a/src/log.h
+++ b/src/log.h
@@ -44,6 +44,13 @@ void log_set_quiet(bool enable);
 int log_add_callback(log_LogFn fn, void *udata, int level);
 int log_add_fp(FILE *fp, int level);
 
-void log_log(int level, const char *file, int line, const char *fmt, ...);
+#define RXI_LOGC_FMT_ATTRIB(n, m)
+
+#if defined __GNUC__
+#  define RXI_LOGC_FMT_ATTRIB(n, m) __attribute__((format(printf, n, m)))
+#endif
+
+
+void log_log(int level, const char *file, int line, const char *fmt, ...) RXI_LOGC_FMT_ATTRIB(4, 5);
 
 #endif