--- util-linux-2.21.orig/include/c.h
+++ util-linux-2.21.1/include/c.h
@@ -115,7 +115,7 @@
 
 #ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
 # ifdef HAVE___PROGNAME
-extern char *__progname;
+extern const char *__progname;
 #  define program_invocation_short_name __progname
 # else
 #  include <string.h>