Index: src/core/raster/qgsrasterlayer.cpp
===================================================================
--- src/core/raster/qgsrasterlayer.cpp	(revision 12398)
+++ src/core/raster/qgsrasterlayer.cpp	(working copy)
@@ -372,6 +372,12 @@
           }
           else break;               // skip if already found a JP2 driver
         }
+
+        if ( myGdalDriverDescription == "GTiff")
+        {
+          glob += " *.tiff";
+        }
+
         theFileFiltersString += myGdalDriverLongName + " (" + glob.toLower() + " " + glob.toUpper() + ");;";
 
         break;            // ... to next driver, if any.