diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index 0d9f7f5..d1e7f3a 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -1868,6 +1868,7 @@
  * simultaneous assignment. there cannot
  * be later use of an earlier lvalue.
  */
+
 int
 vmatch2(Node *l, Node *r)
 {
@@ -1908,7 +1909,18 @@
 		return 0;
 	switch(l->op) {
 	case ONAME:
-		// match each left with all rights
+		switch(l->class) {
+		case PPARAM:
+		case PPARAMREF:
+		case PAUTO:
+			break;
+		default:
+			// assignment to non-stack variable
+			// must be delayed if right has function calls.
+			if(r->ullman >= UINF)
+				return 1;
+			break;
+		}
 		return vmatch2(l, r);
 	case OLITERAL:
 		return 0;
@@ -1937,6 +1949,7 @@
 			n2 = l2->n;
 			if(c2 > c1) {
 				if(vmatch1(n1->left, n2->right)) {
+					// delay assignment to n1->left
 					q = nod(OXXX, N, N);
 					tempname(q, n1->right->type);
 					q = nod(OAS, n1->left, q);
diff --git a/test/bugs/bug159.go b/test/fixedbugs/bug159.go
similarity index 100%
rename from test/bugs/bug159.go
rename to test/fixedbugs/bug159.go
diff --git a/test/golden.out b/test/golden.out
index d4c05db..9875907 100644
--- a/test/golden.out
+++ b/test/golden.out
@@ -147,10 +147,6 @@
 =========== bugs/bug136.go
 BUG: errchk: command succeeded unexpectedly
 
-=========== bugs/bug159.go
-abc: expected 4 5 6 got 4 4 -4
-BUG: bug159
-
 =========== bugs/bug162.go
 123
 BUG: should fail
diff --git a/test/simassign.go b/test/simassign.go
index 1e7d307..ce86d48 100644
--- a/test/simassign.go
+++ b/test/simassign.go
@@ -11,18 +11,19 @@
 func
 printit()
 {
-	print(a,b,c,d,e,f,g,h,i,"\n");
+	println(a,b,c,d,e,f,g,h,i);
 }
 
 func
-testit() bool
+testit(permuteok bool) bool
 {
 	if a+b+c+d+e+f+g+h+i != 45 {
 		print("sum does not add to 45\n");
 		printit();
-		panic();
+		return false;
 	}
-	return	a == 1 &&
+	return	permuteok ||
+		a == 1 &&
 		b == 2 &&
 		c == 3 &&
 		d == 4 &&
@@ -51,22 +52,19 @@
 	h = 8;
 	i = 9;
 
-	if !testit() { panic("init val\n"); }
+	if !testit(false) { panic("init val\n"); }
 
 	for z:=0; z<100; z++ {
 		a,b,c,d, e,f,g,h,i = b,c,d,a, i,e,f,g,h;
 
-		if testit() {
-			if z == 19 {
-				break;
-			}
+		if !testit(z%20 != 19) {
 			print("on ", z, "th iteration\n");
 			printit();
 			panic();
 		}
 	}
 
-	if !testit() {
+	if !testit(false) {
 		print("final val\n");
 		printit();
 		panic();
@@ -76,8 +74,9 @@
 	if a != 2 || b != 1 {
 		panic("bad swap");
 	}
-//BUG	a, b = swap(swap(a, b));
-//	if a != 2 || b != 1 {
-//		panic("bad swap");
-//	}
+
+	a, b = swap(swap(a, b));
+	if a != 2 || b != 1 {
+		panic("bad swap");
+	}
 }