diff --git a/sys/alpha/linux/linux_machdep.c b/sys/alpha/linux/linux_machdep.c
index 3fbbfa9caa5..fc8f96fcc30 100644
--- a/sys/alpha/linux/linux_machdep.c
+++ b/sys/alpha/linux/linux_machdep.c
@@ -6,7 +6,7 @@
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer 
+ *    notice, this list of conditions and the following disclaimer
  *    in this position and unchanged.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ -38,6 +38,7 @@
 #include <vm/pmap.h>
 #include <vm/vm_map.h>
 
+#include <sys/proc.h>
 #include <sys/user.h>
 
 #include <alpha/linux/linux.h>