--- a/netwerk/protocol/http/nsHttpConnectionInfo.cpp
+++ b/netwerk/protocol/http/nsHttpConnectionInfo.cpp
@@ -41,17 +41,25 @@ nsHttpConnectionInfo::SetOriginServer(co
     if (mUsingHttpProxy)
         mHashKey.SetCharAt('P', 0);
     if (mUsingSSL)
         mHashKey.SetCharAt('S', 1);
 
     // NOTE: for transparent proxies (e.g., SOCKS) we need to encode the proxy
     // info in the hash key (this ensures that we will continue to speak the
     // right protocol even if our proxy preferences change).
-    if (!mUsingHttpProxy && ProxyHost()) {
+    //
+    // NOTE: for SSL tunnels add the proxy information to the cache key.
+    // We cannot use the proxy as the host parameter (as we do for non SSL)
+    // because this is a single host tunnel, but we need to include the proxy
+    // information so that a change in proxy config will mean this connection
+    // is not reused
+
+    if ((!mUsingHttpProxy && ProxyHost()) ||
+        (mUsingHttpProxy && mUsingConnect)) {
         mHashKey.AppendLiteral(" (");
         mHashKey.Append(ProxyType());
         mHashKey.Append(':');
         mHashKey.Append(ProxyHost());
         mHashKey.Append(':');
         mHashKey.AppendInt(ProxyPort());
         mHashKey.Append(')');
     }