diff --git a/sim/m32c/trace.c b/sim/m32c/trace.c
index 1888e69122b..2f6373dd5f8 100644
--- a/sim/m32c/trace.c
+++ b/sim/m32c/trace.c
@@ -89,7 +89,7 @@ compare_symbols (const void *ap, const void *bp)
 
 static char opbuf[1000];
 
-static int
+static int ATTRIBUTE_PRINTF (2, 3)
 op_printf (char *buf, char *fmt, ...)
 {
   int ret;
@@ -101,7 +101,7 @@ op_printf (char *buf, char *fmt, ...)
   return ret;
 }
 
-static int
+static int ATTRIBUTE_PRINTF (3, 4)
 op_styled_printf (char *buf, enum disassembler_style style, char *fmt, ...)
 {
   int ret;