# Anyone seen this problem before ?
**URL:** https://community.zeek.org/t/anyone-seen-this-problem-before/227
**Category:** Zeek
**Created:** [April 1, 2002, 5:16pm UTC](https://community.zeek.org/t/anyone-seen-this-problem-before/227 "2002-04-01T17:16:06Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Bill\_Fenner](https://community.zeek.org/u/Bill_Fenner)
#### Post date: [April 1, 2002, 5:16pm UTC](https://community.zeek.org/t/anyone-seen-this-problem-before/227/1 "2002-04-01T17:16:06Z")
If you don't have both flex and bison installed, both libpcap and
bro will use the system lex/yacc. The system lex/yacc don't support
multiple parsers in the same executable.
I wonder if bro's configure script should insist on flex/bison,
since it knows that it'll be linked with libpcap which already has
a parser, and if both are compiled with the system lex/yacc you will
get errors like this.
Bill
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### Author:  [@system](https://community.zeek.org/u/system)
#### Post date: [May 6, 2022, 3:36pm UTC](https://community.zeek.org/t/anyone-seen-this-problem-before/227/2 "2022-05-06T15:36:27Z")