diff --git a/src/utils.c b/src/utils.c
index 9e3414b..a1881f0 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -26,6 +26,7 @@
 #include <stdint.h>
 #include <errno.h>
 #include <stdio.h>
+#include <inttypes.h>
 
 #include <osmocom/core/utils.h>
 #include <osmocom/core/bit64gen.h>
@@ -54,7 +55,7 @@
 	if (str)
 		return str;
 
-	snprintf(namebuf, sizeof(namebuf), "unknown 0x%x", val);
+	snprintf(namebuf, sizeof(namebuf), "unknown 0x%"PRIx32, val);
 	namebuf[sizeof(namebuf) - 1] = '\0';
 	return namebuf;
 }