diff --git a/include/qemu/readline.h b/include/qemu/readline.h
index a89fe4a9a9644c5af3ef50b560e1247b95e08cdf..49efe4e39b491a34a2478327d67c2e53b97b7842 100644
--- a/include/qemu/readline.h
+++ b/include/qemu/readline.h
@@ -5,7 +5,8 @@
 #define READLINE_MAX_CMDS 64
 #define READLINE_MAX_COMPLETIONS 256
 
-typedef void ReadLinePrintfFunc(void *opaque, const char *fmt, ...);
+typedef void GCC_FMT_ATTR(2, 3) ReadLinePrintfFunc(void *opaque,
+                                                   const char *fmt, ...);
 typedef void ReadLineFlushFunc(void *opaque);
 typedef void ReadLineFunc(void *opaque, const char *str,
                           void *readline_opaque);
diff --git a/monitor.c b/monitor.c
index 80456fbe5b01f8633e4a43ce21ec7183ce5572d6..5ba541dc6f1c5756814a308ee30a7e83364a4110 100644
--- a/monitor.c
+++ b/monitor.c
@@ -4888,7 +4888,8 @@ static void sortcmdlist(void)
 /* These functions just adapt the readline interface in a typesafe way.  We
  * could cast function pointers but that discards compiler checks.
  */
-static void monitor_readline_printf(void *opaque, const char *fmt, ...)
+static void GCC_FMT_ATTR(2, 3) monitor_readline_printf(void *opaque,
+                                                       const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);
diff --git a/qemu-io.c b/qemu-io.c
index d6690289b82bcdd19cc420d3c3ce5892b5df8f27..7f459d8ffe4fc655a02e5e16974cb6311789ac03 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -219,7 +219,8 @@ static char *get_prompt(void)
     return prompt;
 }
 
-static void readline_printf_func(void *opaque, const char *fmt, ...)
+static void GCC_FMT_ATTR(2, 3) readline_printf_func(void *opaque,
+                                                    const char *fmt, ...)
 {
     va_list ap;
     va_start(ap, fmt);