diff --git a/src/cmd/compile/internal/ir/node.go b/src/cmd/compile/internal/ir/node.go
index a5a7203faa..850d7343aa 100644
--- a/src/cmd/compile/internal/ir/node.go
+++ b/src/cmd/compile/internal/ir/node.go
@@ -568,7 +568,10 @@ func OuterValue(n Node) Node {
 			continue
 		case OINDEX:
 			nn := nn.(*IndexExpr)
-			if nn.X.Type() != nil && nn.X.Type().IsArray() {
+			if nn.X.Type() == nil {
+				base.Fatalf("OuterValue needs type for %v", nn.X)
+			}
+			if nn.X.Type().IsArray() {
 				n = nn.X
 				continue
 			}
diff --git a/src/cmd/compile/internal/typecheck/typecheck.go b/src/cmd/compile/internal/typecheck/typecheck.go
index 981f4ef1d6..c3a5a3c40f 100644
--- a/src/cmd/compile/internal/typecheck/typecheck.go
+++ b/src/cmd/compile/internal/typecheck/typecheck.go
@@ -1612,6 +1612,14 @@ func checklvalue(n ir.Node, verb string) {
 }
 
 func checkassign(stmt ir.Node, n ir.Node) {
+	// have already complained about n being invalid
+	if n.Type() == nil {
+		if base.Errors() == 0 {
+			base.Fatalf("expected an error about %v", n)
+		}
+		return
+	}
+
 	// Variables declared in ORANGE are assigned on every iteration.
 	if !ir.DeclaredBy(n, stmt) || stmt.Op() == ir.ORANGE {
 		r := ir.OuterValue(n)
@@ -1633,11 +1641,6 @@ func checkassign(stmt ir.Node, n ir.Node) {
 		return
 	}
 
-	// have already complained about n being invalid
-	if n.Type() == nil {
-		return
-	}
-
 	switch {
 	case n.Op() == ir.ODOT && n.(*ir.SelectorExpr).X.Op() == ir.OINDEXMAP:
 		base.Errorf("cannot assign to struct field %v in map", n)