diff --git a/usr.bin/top/machine.c b/usr.bin/top/machine.c
index bd0f7d81d0be..f98f64eb766b 100644
--- a/usr.bin/top/machine.c
+++ b/usr.bin/top/machine.c
@@ -35,6 +35,7 @@
 #include <sys/user.h>
 #include <sys/vmmeter.h>
 
+#include <err.h>
 #include <kvm.h>
 #include <math.h>
 #include <nlist.h>