diff --git a/netwerk/cache/src/nsCacheService.cpp b/netwerk/cache/src/nsCacheService.cpp
index d42c54f66c7f..be201f6c765d 100644
--- a/netwerk/cache/src/nsCacheService.cpp
+++ b/netwerk/cache/src/nsCacheService.cpp
@@ -721,6 +721,8 @@ nsCacheService::IsStorageEnabledForPolicy_Locked(nsCacheStoragePolicy  storagePo
 
 NS_IMETHODIMP nsCacheService::VisitEntries(nsICacheVisitor *visitor)
 {
+    NS_ENSURE_ARG_POINTER(visitor);
+
     nsAutoLock lock(mCacheServiceLock);
 
     if (!(mEnableDiskDevice || mEnableMemoryDevice))