diff --git a/netwerk/dns/nsDNSService2.cpp b/netwerk/dns/nsDNSService2.cpp
index eb53d4829a..e8e257d0f9 100644
--- a/netwerk/dns/nsDNSService2.cpp
+++ b/netwerk/dns/nsDNSService2.cpp
@@ -704,7 +704,9 @@ nsDNSService::PreprocessHostname(bool              aLocalDomain,
 
     // Block access to the "this machine" address.
     if (mBlockQuad0 &&
-        aInput.EqualsASCII("0.0.0.0")) {
+        (aInput.EqualsLiteral("0.0.0.0") ||
+         aInput.EqualsLiteral("::") ||
+         aInput.EqualsLiteral("::0.0.0.0"))) {
         return NS_ERROR_UNKNOWN_HOST;
     }