diff --git a/lib/isc/tests/print_test.c b/lib/isc/tests/print_test.c
index 19bcfaf85e..39432d9166 100644
--- a/lib/isc/tests/print_test.c
+++ b/lib/isc/tests/print_test.c
@@ -118,7 +118,7 @@ ATF_TC_BODY(snprintf, tc) {
 	ATF_CHECK_EQ(n, 4);
 	ATF_CHECK_STREQ(buf, "1750");
 
-	zz = 0xf5f5f5f5f5f5f5f5;
+	zz = 0xf5f5f5f5f5f5f5f5LLU;
 	memset(buf, 0xff, sizeof(buf));
 	n = isc_print_snprintf(buf, sizeof(buf), "0x%"ISC_PRINT_QUADFORMAT"x", zz);
 	ATF_CHECK_EQ(n, 18);