diff --git a/debug.h b/debug.h
index af71d62..6dd2ad8 100644
--- a/debug.h
+++ b/debug.h
@@ -34,7 +34,7 @@
 
 extern unsigned long fio_debug;
 
-void __dprint(int type, const char *str, ...);
+void __dprint(int type, const char *str, ...) __attribute__((format (printf, 2, 3)));
 
 #define dprint(type, str, args...)			\
 	do {						\