diff --git a/openbsc/include/openbsc/debug.h b/openbsc/include/openbsc/debug.h
index 089132e..6ac3a54 100644
--- a/openbsc/include/openbsc/debug.h
+++ b/openbsc/include/openbsc/debug.h
@@ -31,7 +31,7 @@
 #define static_assert(exp, name) typedef int dummy##name [(exp) ? 1 : -1];
 
 char *hexdump(const unsigned char *buf, int len);
-void debugp(unsigned int subsys, char *file, int line, int cont, const char *format, ...);
+void debugp(unsigned int subsys, char *file, int line, int cont, const char *format, ...) __attribute__ ((format (printf, 5, 6)));
 void debug_parse_category_mask(const char* mask);
 void debug_use_color(int use_color);
 void debug_timestamp(int enable);