diff --git a/src/cmd/compile/internal/types2/decl.go b/src/cmd/compile/internal/types2/decl.go
index ab2983c80f..41093cb637 100644
--- a/src/cmd/compile/internal/types2/decl.go
+++ b/src/cmd/compile/internal/types2/decl.go
@@ -477,7 +477,9 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *syntax.TypeDecl, def *Named
 
 	var rhs Type
 	check.later(func() {
-		check.validType(obj.typ)
+		if t, _ := obj.typ.(*Named); t != nil { // type may be invalid
+			check.validType(t)
+		}
 		// If typ is local, an error was already reported where typ is specified/defined.
 		if check.isImportedConstraint(rhs) && !check.allowVersion(check.pkg, 1, 18) {
 			check.versionErrorf(tdecl.Type, "go1.18", "using type constraint %s", rhs)
diff --git a/src/cmd/compile/internal/types2/validtype.go b/src/cmd/compile/internal/types2/validtype.go
index 9cb427b44d..c7f7c13169 100644
--- a/src/cmd/compile/internal/types2/validtype.go
+++ b/src/cmd/compile/internal/types2/validtype.go
@@ -9,7 +9,7 @@ package types2
 // defined types.
 // (Cycles involving alias types, as in "type A = [10]A" are detected
 // earlier, via the objDecl cycle detection mechanism.)
-func (check *Checker) validType(typ Type) {
+func (check *Checker) validType(typ *Named) {
 	check.validType0(typ, nil)
 }
 
diff --git a/src/go/types/decl.go b/src/go/types/decl.go
index a9e89464f6..043f02491d 100644
--- a/src/go/types/decl.go
+++ b/src/go/types/decl.go
@@ -530,7 +530,9 @@ func (check *Checker) typeDecl(obj *TypeName, tdecl *ast.TypeSpec, def *Named) {
 
 	var rhs Type
 	check.later(func() {
-		check.validType(obj.typ)
+		if t, _ := obj.typ.(*Named); t != nil { // type may be invalid
+			check.validType(t)
+		}
 		// If typ is local, an error was already reported where typ is specified/defined.
 		if check.isImportedConstraint(rhs) && !check.allowVersion(check.pkg, 1, 18) {
 			check.errorf(tdecl.Type, _UnsupportedFeature, "using type constraint %s requires go1.18 or later", rhs)
diff --git a/src/go/types/validtype.go b/src/go/types/validtype.go
index d20a2b5bfa..c0e6ee34f6 100644
--- a/src/go/types/validtype.go
+++ b/src/go/types/validtype.go
@@ -9,7 +9,7 @@ package types
 // defined types.
 // (Cycles involving alias types, as in "type A = [10]A" are detected
 // earlier, via the objDecl cycle detection mechanism.)
-func (check *Checker) validType(typ Type) {
+func (check *Checker) validType(typ *Named) {
 	check.validType0(typ, nil)
 }