diff --git a/dlls/winex11.drv/xrender.c b/dlls/winex11.drv/xrender.c
index 554ce25..d85110c 100644
--- a/dlls/winex11.drv/xrender.c
+++ b/dlls/winex11.drv/xrender.c
@@ -1581,8 +1581,6 @@ BOOL X11DRV_AlphaBlend(X11DRV_PDEVICE *devDst, INT xDst, INT yDst, INT widthDst,
         return FALSE;
     }
 
-    if ((blendfn.AlphaFormat & AC_SRC_ALPHA) && blendfn.SourceConstantAlpha != 0xff)
-        FIXME("Ignoring SourceConstantAlpha %d for AC_SRC_ALPHA\n", blendfn.SourceConstantAlpha);
 
     if(dib.dsBm.bmBitsPixel != 32) {
         FIXME("not a 32 bpp dibsection\n");
@@ -1608,6 +1606,20 @@ BOOL X11DRV_AlphaBlend(X11DRV_PDEVICE *devDst, INT xDst, INT yDst, INT widthDst,
         {
             memcpy(dstbits, (char *)dib.dsBm.bmBits + y * dib.dsBm.bmWidthBytes + xSrc * 4,
                    widthSrc * 4);
+
+            if (blendfn.SourceConstantAlpha != 0xff)
+            {
+                BYTE *tmpBits = dstbits;
+                int x;
+
+                for (x = 0; x < widthSrc; x++, tmpBits += 4)
+                {
+                    tmpBits[0] = tmpBits[0] * blendfn.SourceConstantAlpha / 255;
+                    tmpBits[1] = tmpBits[1] * blendfn.SourceConstantAlpha / 255;
+                    tmpBits[2] = tmpBits[2] * blendfn.SourceConstantAlpha / 255;
+                    tmpBits[3] = tmpBits[3] * blendfn.SourceConstantAlpha / 255;
+                }
+            }
             dstbits += (top_down ? -1 : 1) * widthSrc;
         }
     }