diff --git a/openbsd-compat/regress/snprintftest.c b/openbsd-compat/regress/snprintftest.c
index a3134db1c..87b72ca38 100644
--- a/openbsd-compat/regress/snprintftest.c
+++ b/openbsd-compat/regress/snprintftest.c
@@ -25,6 +25,9 @@
 #include <stdarg.h>
 #include <string.h>
 
+/* Suppress format truncation warning since we're explicitly testing that. */
+#pragma GCC diagnostic ignored "-Wformat-truncation"
+
 static int failed = 0;
 
 static void
@@ -50,9 +53,11 @@ main(void)
 {
 	char b[5];
 	char *src = NULL;
+	int ret;
 
-	snprintf(b,5,"123456789");
-	if (b[4] != '\0')
+	memset(b, 'X', sizeof(b));
+	ret = snprintf(b, 5, "123456789");
+	if (ret != 9 || b[4] != '\0')
 		fail("snprintf does not correctly terminate long strings");
 
 	/* check for read overrun on unterminated string */