diff --git a/kernel/x86_64/scal_atom.S b/kernel/x86_64/scal_atom.S
index 11350ea19..284ea4515 100644
--- a/kernel/x86_64/scal_atom.S
+++ b/kernel/x86_64/scal_atom.S
@@ -60,8 +60,10 @@
 #ifdef WINDOWS_ABI
 	movq	40(%rsp), X
 	movq	48(%rsp), INCX
-
+	movq    64(%rsp), %r9
 	movaps	%xmm3, %xmm0
+#else
+	movq	24(%rsp), %r9
 #endif
 
 	SAVEREGISTERS
@@ -73,6 +75,10 @@
 	lea	(, INCX, SIZE), INCX
 	comisd	%xmm0, %xmm1
 	jne	.L100
+	jp	.L100
+
+	cmpq	$1, %r9
+	je	.L100
 
 /* Alpha == ZERO */
 	cmpq	$SIZE, INCX
diff --git a/kernel/x86_64/zscal_atom.S b/kernel/x86_64/zscal_atom.S
index 1649b855b..7713626c9 100644
--- a/kernel/x86_64/zscal_atom.S
+++ b/kernel/x86_64/zscal_atom.S
@@ -74,7 +74,7 @@
 	pxor	%xmm15, %xmm15
 	comisd	%xmm0, %xmm15
 	jne	.L30		# Alpha_r != ZERO
-
+	jp	.L30
 	comisd	%xmm1, %xmm15
 	jne	.L30		# Alpha_i != ZERO