diff --git a/src/mormot.commit.inc b/src/mormot.commit.inc
index b3f534650..9768ba9ae 100644
--- a/src/mormot.commit.inc
+++ b/src/mormot.commit.inc
@@ -1 +1 @@
-'2.1.6338'
+'2.1.6339'
diff --git a/src/net/mormot.net.client.pas b/src/net/mormot.net.client.pas
index a757f9e78..1bcc614cd 100644
--- a/src/net/mormot.net.client.pas
+++ b/src/net/mormot.net.client.pas
@@ -935,6 +935,13 @@   TWinHttpWebSocketClient = class
     destructor Destroy; override;
   end;
 
+var
+  /// global flag to enable HTTP proxy detection at OS level for TWinHttp
+  // - as if Windows 8.1 and newer is detected
+  // - may be useful if {$R Vista.res} manifest is not available in the project,
+  // so only Windows 7 is detected by the executable
+  WinHttpForceProxyDetection: boolean;
+
 {$endif USEWININET}
 
 {$ifdef USELIBCURL}
@@ -2492,7 +2499,8 @@ procedure TWinHttp.InternalConnect(ConnectionTimeOut, SendTimeout, ReceiveTimeou
 begin
   WinHttpApiInitialize;
   if fProxyName = '' then
-    if OSVersion >= wEightOne then
+    if (OSVersion >= wEightOne) or
+       WinHttpForceProxyDetection then
       access := WINHTTP_ACCESS_TYPE_AUTOMATIC_PROXY // Windows 8.1 and newer
     else
       access := WINHTTP_ACCESS_TYPE_NO_PROXY