Index: reactos/win32ss/gdi/ntgdi/bitblt.c
===================================================================
--- reactos/win32ss/gdi/ntgdi/bitblt.c	(revision 74717)
+++ reactos/win32ss/gdi/ntgdi/bitblt.c	(working copy)
@@ -335,15 +335,22 @@
     BOOL Status = FALSE;
     EXLATEOBJ exlo;
     XLATEOBJ *XlateObj = NULL;
-    BOOL UsesSource;
+    BOOL UsesSource, UsesPattern;
     ROP4 rop4;
 
     rop4 = WIN32_ROP4_TO_ENG_ROP4(dwRop4);
 
+    if (!hdcDest)
+    {
+        EngSetLastError(ERROR_INVALID_HANDLE);
+        return FALSE;
+    }
+
     UsesSource = ROP4_USES_SOURCE(rop4);
-    if (!hdcDest || (UsesSource && !hdcSrc))
+    UsesPattern = ROP4_USES_PATTERN(rop4);
+
+    if (!hdcSrc && (UsesSource || UsesPattern))
     {
-        EngSetLastError(ERROR_INVALID_PARAMETER);
         return FALSE;
     }
 
@@ -361,8 +368,8 @@
         /* Make sure the mask bitmap is 1 BPP */
         if (gajBitsPerFormat[psurfMask->SurfObj.iBitmapFormat] != 1)
         {
-            EngSetLastError(ERROR_INVALID_PARAMETER);
             SURFACE_ShareUnlockSurface(psurfMask);
+            EngSetLastError(ERROR_INVALID_HANDLE);
             return FALSE;
         }
     }
@@ -394,6 +401,7 @@
     {
         if(DCSrc) DC_UnlockDc(DCSrc);
         WARN("Invalid destination dc handle (0x%p) passed to NtGdiBitBlt\n", hdcDest);
+        EngSetLastError(ERROR_INVALID_PARAMETER);
         return FALSE;
     }
 
@@ -510,6 +518,11 @@
     DC_UnlockDc(DCDest);
     if(psurfMask) SURFACE_ShareUnlockSurface(psurfMask);
 
+    if (!Status)
+    {
+        EngSetLastError(ERROR_INVALID_PARAMETER);
+    }
+
     return Status;
 }