diff --git a/util/error-report.c b/util/error-report.c
index 5edb2e6040..6e44a55732 100644
--- a/util/error-report.c
+++ b/util/error-report.c
@@ -193,6 +193,7 @@ real_time_iso8601(void)
  * a single phrase, with no newline or trailing punctuation.
  * Prepend the current location and append a newline.
  */
+G_GNUC_PRINTF(2, 0)
 static void vreport(report_type type, const char *fmt, va_list ap)
 {
     gchar *timestr;
diff --git a/util/error.c b/util/error.c
index b6c89d1412..1e7af665b8 100644
--- a/util/error.c
+++ b/util/error.c
@@ -45,6 +45,7 @@ static void error_handle_fatal(Error **errp, Error *err)
     }
 }
 
+G_GNUC_PRINTF(6, 0)
 static void error_setv(Error **errp,
                        const char *src, int line, const char *func,
                        ErrorClass err_class, const char *fmt, va_list ap,