diff --git a/win32ss/user/ntuser/callback.c b/win32ss/user/ntuser/callback.c
index 151a2f12af9..42d50002d33 100644
--- a/win32ss/user/ntuser/callback.c
+++ b/win32ss/user/ntuser/callback.c
@@ -1208,27 +1208,26 @@ co_IntSetupOBM(VOID)
    IntCbFreeMemory(Argument);
 }
 
+//
+//  Called from Kernel GDI sides, no UserLeave/EnterCo required.
+//
 LRESULT
 APIENTRY
 co_UserCBClientPrinterThunk( PVOID pkt, INT InSize, PVOID pvOutData, INT OutSize )
 {
-   ULONG ResultLength;
-   PVOID ResultPointer;
    NTSTATUS Status;
-   UserLeaveCo();
 
    Status = KeUserModeCallback(USER32_CALLBACK_UMPD,
-                               0,
-                               0,
-                               &ResultPointer,
-                               &ResultLength);
+                               pkt,
+                               InSize,
+                               pvOutData,
+                               (PULONG)&OutSize);
 
 
-   UserEnterCo();
-
    if (!NT_SUCCESS(Status))
    {
       ERR("User UMPD callback failed!\n");
+      return 1;
    }
 
    return 0;
diff --git a/win32ss/user/user32/misc/dllmain.c b/win32ss/user/user32/misc/dllmain.c
index a7d0f098b49..6f43b9eeb6b 100644
--- a/win32ss/user/user32/misc/dllmain.c
+++ b/win32ss/user/user32/misc/dllmain.c
@@ -2,6 +2,23 @@
 
 #include <ndk/cmfuncs.h>
 
+#define MAX_USER_MODE_DRV_BUFFER 526
+
+//
+// UMPD Packet Header should match win32ss/include/ntumpd.h
+//
+typedef struct _UMPDPKTHEAD
+{
+    INT       Size;
+    INT       Index;
+    INT       RetSize;
+    DWORD     Reserved;
+    HUMPD     humpd;
+    ULONG_PTR Buffer[];
+} UMPDPKTHEAD, *PUMPDPKTHEAD;
+
+INT WINAPI GdiPrinterThunk(PUMPDPKTHEAD,PVOID,INT);
+
 WINE_DEFAULT_DEBUG_CHANNEL(user32);
 
 #define KEY_LENGTH 1024
@@ -667,6 +684,30 @@ NTSTATUS WINAPI User32CallLPKFromKernel(PVOID Arguments, ULONG ArgumentLength)
 
 NTSTATUS WINAPI User32CallUMPDFromKernel(PVOID Arguments, ULONG ArgumentLength)
 {
-    // = GdiPrinterThunk( , , );
-    return ZwCallbackReturn(Arguments, ArgumentLength, STATUS_SUCCESS);
+    DWORD Buffer[MAX_USER_MODE_DRV_BUFFER];
+    INT cbSize = 0;
+    NTSTATUS Status = STATUS_SUCCESS;
+    PUMPDPKTHEAD pkt, pktOut = NULL;
+
+    pkt = (PUMPDPKTHEAD)Arguments;
+
+    if ( pkt->RetSize <= sizeof(Buffer) )
+    {
+        pktOut = (PUMPDPKTHEAD)Buffer;
+
+        if ( (GdiPrinterThunk( pkt, pktOut, pkt->RetSize ) == GDI_ERROR) )
+        {
+            pktOut = NULL;
+            Status = STATUS_UNSUCCESSFUL;
+        }
+        else
+        {
+            cbSize = pkt->RetSize;
+        }
+    }
+    else
+    {
+       Status = STATUS_NO_MEMORY;   
+    }
+    return ZwCallbackReturn( pktOut, cbSize, Status );
 }