diff --git a/src/log.h b/src/log.h
index 96a6647..772b08d 100644
--- a/src/log.h
+++ b/src/log.h
@@ -40,6 +40,7 @@ void uh_log_close();
 #define uh_log_info(fmt...)      uh_log(LOG_INFO, fmt)
 #define uh_log_err(fmt...)       uh_log(LOG_ERR, fmt)
 
-void  __uh_log(const char *filename, int line, int priority, const char *fmt, ...);
+void  __uh_log(const char *filename, int line, int priority, const char *fmt, ...)
+    __attribute__((format(printf, 4, 5)));
 
 #endif