Index: esh-grammar.y
===================================================================
--- esh-grammar.y	(revision 80)
+++ esh-grammar.y	(working copy)
@@ -79,6 +79,9 @@
 /* Called by parser when command line is complete */
 static void cmdline_complete(struct esh_command_line *);
 
+/* work-around for bug in flex 2.31 and later */
+static void yyunput (int c,char *buf_ptr  ) __attribute__((unused));
+
 %}
 
 /* LALR stack types */
@@ -202,6 +205,7 @@
     }
 
 #define YY_NO_UNPUT
+#define YY_NO_INPUT
 #include "lex.yy.c"
 
 static void