diff --git a/kernel/x86/zscal_sse.S b/kernel/x86/zscal_sse.S
index e011c98f5..89e36251e 100644
--- a/kernel/x86/zscal_sse.S
+++ b/kernel/x86/zscal_sse.S
@@ -87,6 +87,7 @@
 	xorps	%xmm7, %xmm7
 	comiss	%xmm0, %xmm7
 	jne	.L100		# Alpha_r != ZERO
+	jp	.L100		# Alpha_r NaN
 
 	comiss	%xmm1, %xmm7
 	jne	.L100		# Alpha_i != ZERO
diff --git a/kernel/x86/zscal_sse2.S b/kernel/x86/zscal_sse2.S
index cc7ab6686..0bc61b209 100644
--- a/kernel/x86/zscal_sse2.S
+++ b/kernel/x86/zscal_sse2.S
@@ -98,6 +98,7 @@
 	xorps	%xmm7, %xmm7
 	comisd	%xmm0, %xmm7
 	jne	.L100
+	jp	.L100
 
 	comisd	%xmm1, %xmm7
 	jne	.L100