diff --git a/cl/rewrite_internal_test.go b/cl/rewrite_internal_test.go
new file mode 100644
index 00000000..6c542bc3
--- /dev/null
+++ b/cl/rewrite_internal_test.go
@@ -0,0 +1,67 @@
+//go:build !llgo
+// +build !llgo
+
+package cl
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"runtime"
+	"strings"
+	"testing"
+
+	gpackages "github.com/goplus/gogen/packages"
+	llssa "github.com/goplus/llgo/ssa"
+	"github.com/goplus/llgo/ssa/ssatest"
+	"golang.org/x/tools/go/ssa"
+	"golang.org/x/tools/go/ssa/ssautil"
+)
+
+func init() {
+	llssa.Initialize(llssa.InitAll | llssa.InitNative)
+}
+
+func compileWithRewrites(t *testing.T, src string, rewrites map[string]string) string {
+	t.Helper()
+	fset := token.NewFileSet()
+	file, err := parser.ParseFile(fset, "rewrite.go", src, 0)
+	if err != nil {
+		t.Fatalf("parse failed: %v", err)
+	}
+	importer := gpackages.NewImporter(fset)
+	mode := ssa.SanityCheckFunctions | ssa.InstantiateGenerics
+	pkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer}, fset,
+		types.NewPackage(file.Name.Name, file.Name.Name), []*ast.File{file}, mode)
+	if err != nil {
+		t.Fatalf("build package failed: %v", err)
+	}
+	prog := ssatest.NewProgramEx(t, nil, importer)
+	prog.TypeSizes(types.SizesFor("gc", runtime.GOARCH))
+	ret, _, err := NewPackageEx(prog, nil, rewrites, pkg, []*ast.File{file})
+	if err != nil {
+		t.Fatalf("NewPackageEx failed: %v", err)
+	}
+	return ret.String()
+}
+
+func TestRewriteGlobalStrings(t *testing.T) {
+	const src = `package rewritepkg
+var VarInit = "original_value"
+var VarPlain string
+func Use() string { return VarInit + VarPlain }
+`
+	ir := compileWithRewrites(t, src, map[string]string{
+		"VarInit":  "rewrite_init",
+		"VarPlain": "rewrite_plain",
+	})
+	if strings.Contains(ir, "original_value") {
+		t.Fatalf("original initializer still present:\n%s", ir)
+	}
+	for _, want := range []string{`c"rewrite_init"`, `c"rewrite_plain"`} {
+		if !strings.Contains(ir, want) {
+			t.Fatalf("missing %s in IR:\n%s", want, ir)
+		}
+	}
+}