Index: usr.bin/lex/flex.skl
===================================================================
--- usr.bin/lex/flex.skl	(revision 251159)
+++ usr.bin/lex/flex.skl	(working copy)
@@ -1222,6 +1222,9 @@
 %*
 
 	{
+	if ( ! b )
+		YY_FATAL_ERROR( "NULL buffer passed to yy_init_buffer()" );
+
 	yy_flush_buffer( b );
 
 	b->yy_input_file = file;