diff --git a/src/runtime/sys_darwin_386.s b/src/runtime/sys_darwin_386.s
index 9e45f8a002465..83f4709f385fb 100644
--- a/src/runtime/sys_darwin_386.s
+++ b/src/runtime/sys_darwin_386.s
@@ -201,6 +201,11 @@ systime:
 	MOVL	$0, 8(SP)	// time zone pointer
 	MOVL	$116, AX
 	INT	$0x80
+	CMPL	AX, $0
+	JNE	inreg
+	MOVL	12(SP), AX
+	MOVL	16(SP), DX
+inreg:
 	// sec is in AX, usec in DX
 	// convert to DX:AX nsec
 	MOVL	DX, BX
diff --git a/src/runtime/sys_darwin_amd64.s b/src/runtime/sys_darwin_amd64.s
index 7b9cf6a3bcdc2..e09b906ba571f 100644
--- a/src/runtime/sys_darwin_amd64.s
+++ b/src/runtime/sys_darwin_amd64.s
@@ -155,10 +155,15 @@ timeloop:
 
 systime:
 	// Fall back to system call (usually first call in this thread).
-	MOVQ	SP, DI	// must be non-nil, unused
+	MOVQ	SP, DI
 	MOVQ	$0, SI
 	MOVL	$(0x2000000+116), AX
 	SYSCALL
+	CMPQ	AX, $0
+	JNE	inreg
+	MOVQ	0(SP), AX
+	MOVL	8(SP), DX
+inreg:
 	// sec is in AX, usec in DX
 	// return nsec in AX
 	IMULQ	$1000000000, AX