--- a/netwerk/base/src/nsProtocolProxyService.cpp
+++ b/netwerk/base/src/nsProtocolProxyService.cpp
@@ -1553,17 +1553,22 @@ nsProtocolProxyService::Resolve_Internal
 
     // Proxy auto config magic...
     if (mProxyConfig == PROXYCONFIG_PAC || mProxyConfig == PROXYCONFIG_WPAD) {
         // Do not query PAC now.
         *usePACThread = true;
         return NS_OK;
     }
 
-    // proxy info values
+    // If we aren't in manual proxy configuration mode then we don't
+    // want to honor any manual specific prefs that might be still set
+    if (mProxyConfig != PROXYCONFIG_MANUAL)
+        return NS_OK;
+
+    // proxy info values for manual configuration mode
     const char *type = nullptr;
     const nsACString *host = nullptr;
     int32_t port = -1;
 
     uint32_t proxyFlags = 0;
 
     if ((flags & RESOLVE_PREFER_SOCKS_PROXY) &&
         !mSOCKSProxyHost.IsEmpty() && mSOCKSProxyPort > 0) {