diff --git a/dom/crypto/WebCryptoTask.cpp b/dom/crypto/WebCryptoTask.cpp
index cbb95f966b..b8239b9046 100644
--- a/dom/crypto/WebCryptoTask.cpp
+++ b/dom/crypto/WebCryptoTask.cpp
@@ -152,7 +152,7 @@ GetAlgorithmName(JSContext* aCx, const OOS& aAlgorithm, nsString& aName)
   }
 
   if (!NormalizeToken(aName, aName)) {
-    return NS_ERROR_DOM_SYNTAX_ERR;
+    return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
   }
 
   return NS_OK;