diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index cddc37a5415a..85105ec76259 100644
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -252,7 +252,7 @@ asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data
 			break;
 
 		switch (addr) { 
-		case 0 ... sizeof(struct user_regs_struct):
+		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
 			tmp = getreg(child, addr);
 			break;
 		case offsetof(struct user, u_debugreg[0]):
@@ -297,7 +297,7 @@ asmlinkage long sys_ptrace(long request, long pid, unsigned long addr, long data
 			break;
 
 		switch (addr) { 
-		case 0 ... sizeof(struct user_regs_struct): 
+		case 0 ... sizeof(struct user_regs_struct) - sizeof(long):
 			ret = putreg(child, addr, data);
 			break;
 		/* Disallows to set a breakpoint into the vsyscall */