diff -r dee5afe5301f -r 3f74d0d4af4c src/opengl/qglframebufferobject.cpp
--- a/src/opengl/qglframebufferobject.cpp	Mon Mar 15 12:43:09 2010 +0200
+++ b/src/opengl/qglframebufferobject.cpp	Thu Apr 08 14:19:33 2010 +0300
@@ -329,6 +329,13 @@
     } else if (attachment == QGLFramebufferObject::Depth) {
         fboFormat.setDepth(true);
     }
+
+    GLenum format = f->format().internalTextureFormat();
+    reqAlpha = (format != GL_RGB
+#ifndef QT_OPENGL_ES
+                && format != GL_RGB5 && format != GL_RGB8
+#endif
+    );
 }
 
 QGLContext *QGLFBOGLPaintDevice::context() const