diff --git a/src/htsbuf.h b/src/htsbuf.h
index b355ce1f..50c8d3ac 100644
--- a/src/htsbuf.h
+++ b/src/htsbuf.h
@@ -51,7 +51,8 @@ void htsbuf_queue_flush(htsbuf_queue_t *hq);
 
 void htsbuf_vqprintf(htsbuf_queue_t *hq, const char *fmt, va_list ap);
 
-void htsbuf_qprintf(htsbuf_queue_t *hq, const char *fmt, ...);
+void htsbuf_qprintf(htsbuf_queue_t *hq, const char *fmt, ...)
+  __attribute__((format(printf,2,3)));
 
 void htsbuf_append(htsbuf_queue_t *hq, const void *buf, size_t len);