--- xulrunner-9.0.1/mozilla/modules/libpr0n/decoders/nsPNGDecoder.h.orig	2011-12-21 00:28:33.000000000 +0100
+++ xulrunner-9.0.1/mozilla/modules/libpr0n/decoders/nsPNGDecoder.h	2012-01-16 18:43:35.830209631 +0100
@@ -76,7 +76,7 @@
   // Checks if the info header contains valid information
   bool HasValidInfo() const 
   {
-    return mInfo && mInfo->valid;
+    return mInfo && png_get_valid(mPNG, mInfo, 0xFFFFFFFFU);
   }
 
   // Obtain the pixel depth if available or 0 otherwise
@@ -85,7 +85,8 @@
     if (!mInfo) {
       return 0;
     }
-    return mInfo->pixel_depth;
+    // XXX: shouldn't png_get_pixel_depth() be available?
+    return png_get_bit_depth(mPNG, mInfo) * png_get_channels(mPNG, mInfo);
   }
 
 public: