diff --git a/quic/test_tools/quic_test_utils.cc b/quic/test_tools/quic_test_utils.cc
index b3bd2bb..e033ac5 100644
--- a/quic/test_tools/quic_test_utils.cc
+++ b/quic/test_tools/quic_test_utils.cc
@@ -894,6 +894,7 @@
   if (!versions) {
     versions = &supported_versions;
   }
+  EXPECT_FALSE(versions->empty());
   ParsedQuicVersion version = (*versions)[0];
   if (QuicVersionHasLongHeaderLengths(version.transport_version) &&
       version_flag) {