diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1d9db15fdc692..a5f02d03c585a 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -108,7 +108,8 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL)
 
 	/* IRQs are off. */
 	movq	%rsp, %rdi
-	movq	%rax, %rsi
+	/* Sign extend the lower 32bit as syscall numbers are treated as int */
+	movslq	%eax, %rsi
 	call	do_syscall_64		/* returns with IRQs disabled */
 
 	/*