diff --git a/lib/krb5/changepw.c b/lib/krb5/changepw.c
index 648675ef4..cf09ea296 100644
--- a/lib/krb5/changepw.c
+++ b/lib/krb5/changepw.c
@@ -138,6 +138,11 @@ out2:
     return ret;
 }
 
+static void
+str2data (krb5_data *d,
+	  const char *fmt,
+	  ...) __attribute__ ((format (printf, 2, 3)));
+
 static void
 str2data (krb5_data *d,
 	  const char *fmt,