diff --git a/src/cmd/compile/internal/types2/assignments.go b/src/cmd/compile/internal/types2/assignments.go
index 2eecce94c8..c774658a23 100644
--- a/src/cmd/compile/internal/types2/assignments.go
+++ b/src/cmd/compile/internal/types2/assignments.go
@@ -373,11 +373,9 @@ func (check *Checker) initVars(lhs []*Var, orig_rhs []syntax.Expr, returnStmt sy
 	}
 
 	if commaOk {
-		var a [2]Type
-		for i := range a {
-			a[i] = check.initVar(lhs[i], rhs[i], context)
-		}
-		check.recordCommaOkTypes(orig_rhs[0], a)
+		check.initVar(lhs[0], rhs[0], context)
+		check.initVar(lhs[1], rhs[1], context)
+		check.recordCommaOkTypes(orig_rhs[0], rhs)
 		return
 	}
 
@@ -412,11 +410,9 @@ func (check *Checker) assignVars(lhs, orig_rhs []syntax.Expr) {
 	}
 
 	if commaOk {
-		var a [2]Type
-		for i := range a {
-			a[i] = check.assignVar(lhs[i], rhs[i])
-		}
-		check.recordCommaOkTypes(orig_rhs[0], a)
+		check.assignVar(lhs[0], rhs[0])
+		check.assignVar(lhs[1], rhs[1])
+		check.recordCommaOkTypes(orig_rhs[0], rhs)
 		return
 	}
 
diff --git a/src/cmd/compile/internal/types2/check.go b/src/cmd/compile/internal/types2/check.go
index 33b57c0c2c..0c9e80e014 100644
--- a/src/cmd/compile/internal/types2/check.go
+++ b/src/cmd/compile/internal/types2/check.go
@@ -504,22 +504,27 @@ func (check *Checker) recordBuiltinType(f syntax.Expr, sig *Signature) {
 	}
 }
 
-func (check *Checker) recordCommaOkTypes(x syntax.Expr, a [2]Type) {
+// recordCommaOkTypes updates recorded types to reflect that x is used in a commaOk context
+// (and therefore has tuple type).
+func (check *Checker) recordCommaOkTypes(x syntax.Expr, a []*operand) {
 	assert(x != nil)
-	if a[0] == nil || a[1] == nil {
+	assert(len(a) == 2)
+	if a[0].mode == invalid {
 		return
 	}
-	assert(isTyped(a[0]) && isTyped(a[1]) && (isBoolean(a[1]) || a[1] == universeError))
+	t0, t1 := a[0].typ, a[1].typ
+	assert(isTyped(t0) && isTyped(t1) && (isBoolean(t1) || t1 == universeError))
 	if m := check.Types; m != nil {
 		for {
 			tv := m[x]
 			assert(tv.Type != nil) // should have been recorded already
 			pos := x.Pos()
 			tv.Type = NewTuple(
-				NewVar(pos, check.pkg, "", a[0]),
-				NewVar(pos, check.pkg, "", a[1]),
+				NewVar(pos, check.pkg, "", t0),
+				NewVar(pos, check.pkg, "", t1),
 			)
 			m[x] = tv
+			// if x is a parenthesized expression (p.X), update p.X
 			p, _ := x.(*syntax.ParenExpr)
 			if p == nil {
 				break
@@ -535,8 +540,8 @@ func (check *Checker) recordCommaOkTypes(x syntax.Expr, a [2]Type) {
 			assert(tv.Type != nil) // should have been recorded already
 			pos := x.Pos()
 			tv.Type = NewTuple(
-				NewVar(pos, check.pkg, "", a[0]),
-				NewVar(pos, check.pkg, "", a[1]),
+				NewVar(pos, check.pkg, "", t0),
+				NewVar(pos, check.pkg, "", t1),
 			)
 			x.SetTypeInfo(tv)
 			p, _ := x.(*syntax.ParenExpr)
diff --git a/src/go/types/assignments.go b/src/go/types/assignments.go
index 8d12df81a0..373b8ec231 100644
--- a/src/go/types/assignments.go
+++ b/src/go/types/assignments.go
@@ -365,11 +365,9 @@ func (check *Checker) initVars(lhs []*Var, origRHS []ast.Expr, returnStmt ast.St
 	}
 
 	if commaOk {
-		var a [2]Type
-		for i := range a {
-			a[i] = check.initVar(lhs[i], rhs[i], context)
-		}
-		check.recordCommaOkTypes(origRHS[0], a)
+		check.initVar(lhs[0], rhs[0], context)
+		check.initVar(lhs[1], rhs[1], context)
+		check.recordCommaOkTypes(origRHS[0], rhs)
 		return
 	}
 
@@ -394,11 +392,9 @@ func (check *Checker) assignVars(lhs, origRHS []ast.Expr) {
 	}
 
 	if commaOk {
-		var a [2]Type
-		for i := range a {
-			a[i] = check.assignVar(lhs[i], rhs[i])
-		}
-		check.recordCommaOkTypes(origRHS[0], a)
+		check.assignVar(lhs[0], rhs[0])
+		check.assignVar(lhs[1], rhs[1])
+		check.recordCommaOkTypes(origRHS[0], rhs)
 		return
 	}
 
diff --git a/src/go/types/check.go b/src/go/types/check.go
index b862ba57b8..83e2995bbc 100644
--- a/src/go/types/check.go
+++ b/src/go/types/check.go
@@ -478,20 +478,24 @@ func (check *Checker) recordBuiltinType(f ast.Expr, sig *Signature) {
 	}
 }
 
-func (check *Checker) recordCommaOkTypes(x ast.Expr, a [2]Type) {
+// recordCommaOkTypes updates recorded types to reflect that x is used in a commaOk context
+// (and therefore has tuple type).
+func (check *Checker) recordCommaOkTypes(x ast.Expr, a []*operand) {
 	assert(x != nil)
-	if a[0] == nil || a[1] == nil {
+	assert(len(a) == 2)
+	if a[0].mode == invalid {
 		return
 	}
-	assert(isTyped(a[0]) && isTyped(a[1]) && (isBoolean(a[1]) || a[1] == universeError))
+	t0, t1 := a[0].typ, a[1].typ
+	assert(isTyped(t0) && isTyped(t1) && (isBoolean(t1) || t1 == universeError))
 	if m := check.Types; m != nil {
 		for {
 			tv := m[x]
 			assert(tv.Type != nil) // should have been recorded already
 			pos := x.Pos()
 			tv.Type = NewTuple(
-				NewVar(pos, check.pkg, "", a[0]),
-				NewVar(pos, check.pkg, "", a[1]),
+				NewVar(pos, check.pkg, "", t0),
+				NewVar(pos, check.pkg, "", t1),
 			)
 			m[x] = tv
 			// if x is a parenthesized expression (p.X), update p.X