diff --git a/parse.yacc b/parse.yacc
index c4b85d293..6d64723fd 100644
--- a/parse.yacc
+++ b/parse.yacc
@@ -32,6 +32,7 @@
 *******************************************************************************/
 #include <stdio.h>
 #include <sys/types.h>
+#include <sys/param.h>
 #include "sudo.h"
 
 extern int yylineno;