Index: gedit/gedit-convert.c
===================================================================
--- gedit/gedit-convert.c	(revision 6350)
+++ gedit/gedit-convert.c	(working copy)
@@ -103,6 +103,15 @@
          * changing g_utf8_valdidate() wouldn't be API compatible even if I 
          * thought it was right
 	 */			
+
+	{
+		int i;
+		for (i = 0;i < *new_len;i++)
+			if (!converted_contents[i]) {
+				converted_contents[i] = '?';
+			}
+	}
+
 	if ((conv_error != NULL) || 
 	    !g_utf8_validate (converted_contents, *new_len, NULL) ||
 	    (bytes_read != len))
