diff --git a/sys/i386/include/counter.h b/sys/i386/include/counter.h
index 1b3fc4c638e..2a54e2b725e 100644
--- a/sys/i386/include/counter.h
+++ b/sys/i386/include/counter.h
@@ -35,6 +35,7 @@
 #ifdef INVARIANTS
 #include <sys/proc.h>
 #endif
+#include <sys/systm.h>
 #include <machine/md_var.h>
 #include <machine/specialreg.h>