diff --git a/libwvdrmengine/cdm/core/test/cdm_engine_test.cpp b/libwvdrmengine/cdm/core/test/cdm_engine_test.cpp
index 8455ad4b..e175896c 100644
--- a/libwvdrmengine/cdm/core/test/cdm_engine_test.cpp
+++ b/libwvdrmengine/cdm/core/test/cdm_engine_test.cpp
@@ -516,7 +516,7 @@ TEST_F(WvCdmEnginePreProvTestUat, ProvisioningServiceCertificateValidTest) {
 TEST_F(WvCdmEnginePreProvTestUat, ProvisioningServiceCertificateInvalidTest) {
   std::string certificate = g_provisioning_service_certificate;
   // Add four nulls to the beginning of the cert to invalidate it
-  certificate.insert(0, 4, 0);
+  certificate.insert(0, 4, '\0');
 
   ASSERT_NE(cdm_engine_.ValidateServiceCertificate(certificate), NO_ERROR);
 };