diff --git a/src/libstrongswan/tests/test_utils.c b/src/libstrongswan/tests/test_utils.c
index f7cb605fa..ec9baf158 100644
--- a/src/libstrongswan/tests/test_utils.c
+++ b/src/libstrongswan/tests/test_utils.c
@@ -119,7 +119,7 @@ START_TEST(test_htoun)
 	chunk_t net64, expected;
 	u_int16_t host16 = 513;
 	u_int32_t net16 = 0, host32 = 67305985;
-	u_int64_t net32 = 0, host64 = 578437695752307201;
+	u_int64_t net32 = 0, host64 = 578437695752307201ULL;
 
 	net64 = chunk_alloca(16);
 	memset(net64.ptr, 0, net64.len);
@@ -159,7 +159,7 @@ START_TEST(test_untoh)
 	net = chunk_from_chars(0x00, 0x00, 0x00, 0x00, 0x08, 0x07, 0x06, 0x05,
 						   0x04, 0x03, 0x02, 0x01, 0x00, 0x00, 0x00, 0x00);
 	host64 = untoh64(net.ptr + 4);
-	ck_assert(host64 == 578437695752307201);
+	ck_assert(host64 == 578437695752307201ULL);
 }
 END_TEST