diff --git a/lib/libc/gen/sysconf.c b/lib/libc/gen/sysconf.c
index 7df2f51494e5..154c329a4bf4 100644
--- a/lib/libc/gen/sysconf.c
+++ b/lib/libc/gen/sysconf.c
@@ -39,6 +39,7 @@ static char sccsid[] = "@(#)sysconf.c	8.2 (Berkeley) 3/20/94";
 #endif /* LIBC_SCCS and not lint */
 
 #include <sys/param.h>
+#include <sys/user.h>
 #include <sys/sysctl.h>
 #include <sys/resource.h>