diff --git a/arch/amd64/include/u.h b/arch/amd64/include/u.h
index eb2bb53..58e3317 100644
--- a/arch/amd64/include/u.h
+++ b/arch/amd64/include/u.h
@@ -25,7 +25,7 @@ typedef long			ssize_t;
 typedef int32_t			pid_t;
 typedef uint32_t		Rune;
 typedef union FPdbleword	FPdbleword;
-typedef uintptr			jmp_buf[10]; // for registers.
+typedef uintptr_t		jmp_buf[10]; // for registers.
 typedef long			off_t;
 typedef long			ptrdiff_t;