diff --git a/WebCore/ChangeLog b/WebCore/ChangeLog
index 439a99f..5d6b786 100644
--- a/WebCore/ChangeLog
+++ b/WebCore/ChangeLog
@@ -1,3 +1,12 @@
+2010-07-27  Andreas Kling  <andreas.kling@nokia.com>
+
+        Reviewed by NOBODY (OOPS!).
+
+        [Qt] putImageData(): Fast premultiply() if alpha == 255
+
+        * platform/graphics/qt/ImageBufferQt.cpp:
+        (WebCore::premultiply): Do nothing for opaque pixels.
+
 2010-07-27  Simon Fraser  <simon.fraser@apple.com>

         Reviewed by Darin Adler.
diff --git a/WebCore/platform/graphics/qt/ImageBufferQt.cpp b/WebCore/platform/graphics/qt/ImageBufferQt.cpp
index bd272db..e0e2de6 100644
--- a/WebCore/platform/graphics/qt/ImageBufferQt.cpp
+++ b/WebCore/platform/graphics/qt/ImageBufferQt.cpp
@@ -240,6 +240,8 @@ PassRefPtr<ImageData> ImageBuffer::getPremultipliedImageData(const IntRect& rect
 static inline unsigned int premultiply(unsigned int x)
 {
     unsigned int a = x >> 24;
+    if (a == 255)
+        return x;
     unsigned int t = (x & 0xff00ff) * a;
     t = (t + ((t >> 8) & 0xff00ff) + 0x800080) >> 8;
     t &= 0xff00ff;