diff --git a/storage/mozStorageConnection.cpp b/storage/mozStorageConnection.cpp
index 340fa527d41d..b45fddda0717 100644
--- a/storage/mozStorageConnection.cpp
+++ b/storage/mozStorageConnection.cpp
@@ -2162,7 +2162,7 @@ Connection::CreateFunction(const nsACString& aFunctionName,
   // Check to see if this function is already defined.  We only check the name
   // because a function can be defined with the same body but different names.
   SQLiteMutexAutoLock lockedScope(sharedDBMutex);
-  NS_ENSURE_FALSE(mFunctions.Get(aFunctionName, nullptr), NS_ERROR_FAILURE);
+  NS_ENSURE_FALSE(mFunctions.Contains(aFunctionName), NS_ERROR_FAILURE);
 
   int srv = ::sqlite3_create_function(
       mDBConn, nsPromiseFlatCString(aFunctionName).get(), aNumArguments,