--- Canvas.h.orig	Wed Dec  5 17:28:40 2012
+++ Canvas.h	Wed Dec  5 17:29:05 2012
@@ -70,7 +70,7 @@ class Window : public Canvas
 class Image : public Canvas
 {
  public:
-  Image( const char* file, bool alpha=false );
+  explicit Image( const char* file, bool alpha=false );
 };
 
 
