diff --git a/lib/com_err/lex.l b/lib/com_err/lex.l
index b68814b21..b17c9d67a 100644
--- a/lib/com_err/lex.l
+++ b/lib/com_err/lex.l
@@ -53,6 +53,7 @@ static int getstring(void);
 
 %}
 
+%option nounput
 
 %%
 et			{ return ET; }