diff --git a/sys/ia64/ia64/sscdisk.c b/sys/ia64/ia64/sscdisk.c
index 8baa0517bc9e..000cefa1d57a 100644
--- a/sys/ia64/ia64/sscdisk.c
+++ b/sys/ia64/ia64/sscdisk.c
@@ -26,6 +26,7 @@
 #include <sys/mutex.h>
 #include <sys/queue.h>
 #include <sys/sysctl.h>
+#include <sys/proc.h>
 #include <vm/vm.h>
 #include <vm/vm_kern.h>
 #include <vm/vm_page.h>