diff --git a/src/cmd/compile/internal/types2/stmt.go b/src/cmd/compile/internal/types2/stmt.go
index f87ef11b98..3e5c9cb6cd 100644
--- a/src/cmd/compile/internal/types2/stmt.go
+++ b/src/cmd/compile/internal/types2/stmt.go
@@ -446,26 +446,23 @@ func (check *Checker) stmt(ctxt stmtContext, s syntax.Stmt) {
 		check.assignment(&val, uch.elem, "send")
 
 	case *syntax.AssignStmt:
-		lhs := unpackExpr(s.Lhs)
 		if s.Rhs == nil {
 			// x++ or x--
-			if len(lhs) != 1 {
-				check.errorf(s, InvalidSyntaxTree, "%s%s requires one operand", s.Op, s.Op)
-				return
-			}
+			// (no need to call unpackExpr as s.Lhs must be single-valued)
 			var x operand
-			check.expr(&x, lhs[0])
+			check.expr(&x, s.Lhs)
 			if x.mode == invalid {
 				return
 			}
 			if !allNumeric(x.typ) {
-				check.errorf(lhs[0], NonNumericIncDec, invalidOp+"%s%s%s (non-numeric type %s)", lhs[0], s.Op, s.Op, x.typ)
+				check.errorf(s.Lhs, NonNumericIncDec, invalidOp+"%s%s%s (non-numeric type %s)", s.Lhs, s.Op, s.Op, x.typ)
 				return
 			}
-			check.assignVar(lhs[0], &x)
+			check.assignVar(s.Lhs, &x)
 			return
 		}
 
+		lhs := unpackExpr(s.Lhs)
 		rhs := unpackExpr(s.Rhs)
 		switch s.Op {
 		case 0: