diff --git a/stringer.go b/stringer.go
index ccfb304..a9273e9 100644
--- a/stringer.go
+++ b/stringer.go
@@ -273,7 +273,7 @@ func (g *Generator) parsePackage(directory string, names []string, text interfac
 // check type-checks the package. The package must be OK to proceed.
 func (pkg *Package) check(fs *token.FileSet, astFiles []*ast.File) {
 	pkg.defs = make(map[*ast.Ident]types.Object)
-	config := types.Config{Importer: importer.Default(), FakeImportC: true}
+	config := types.Config{Importer: importer.For("source", nil), FakeImportC: true}
 	info := &types.Info{
 		Defs: pkg.defs,
 	}