diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 47ce9a2..0607119 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -12,6 +12,7 @@
 #include <asm/system.h>
 #include <asm/tlbflush.h>
 #include <asm/tlb.h>
+#include <asm/proto.h>
 
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);