diff --git a/.changes/unreleased/BUG FIXES-20260724-142353.yaml b/.changes/unreleased/BUG FIXES-20260724-142353.yaml
new file mode 100644
index 000000000..531a095b3
--- /dev/null
+++ b/.changes/unreleased/BUG FIXES-20260724-142353.yaml	
@@ -0,0 +1,5 @@
+kind: BUG FIXES
+body: 'helper/resource: Fix persisted working directory copying on Windows.'
+time: 2026-07-24T14:23:53.759+02:00
+custom:
+    Issue: "672"
diff --git a/internal/plugintest/util.go b/internal/plugintest/util.go
index 856163afe..b17d62d63 100644
--- a/internal/plugintest/util.go
+++ b/internal/plugintest/util.go
@@ -8,7 +8,6 @@ import (
 	"io"
 	"io/fs"
 	"os"
-	"path"
 	"path/filepath"
 	"strings"
 	"testing"
@@ -119,8 +118,8 @@ func CopyDir(src, dest, baseDirName string) error {
 	}
 
 	for _, dirEntry := range dirEntries {
-		srcFilepath := path.Join(src, dirEntry.Name())
-		destFilepath := path.Join(dest, dirEntry.Name())
+		srcFilepath := filepath.Join(src, dirEntry.Name())
+		destFilepath := filepath.Join(dest, dirEntry.Name())
 
 		if !strings.Contains(srcFilepath, baseDirName) {
 			continue
diff --git a/internal/plugintest/util_test.go b/internal/plugintest/util_test.go
index 287f326bc..d771c11d1 100644
--- a/internal/plugintest/util_test.go
+++ b/internal/plugintest/util_test.go
@@ -123,3 +123,29 @@ func dirEntryComparer(t *testing.T) cmp.Option {
 		return true
 	})
 }
+
+func TestCopyDirWithBaseDirName(t *testing.T) {
+	t.Parallel()
+
+	srcDir := t.TempDir()
+	baseDir := filepath.Join(srcDir, "work")
+
+	if err := os.MkdirAll(baseDir, 0o755); err != nil {
+		t.Fatalf("cannot create base directory: %s", err)
+	}
+
+	if err := os.WriteFile(filepath.Join(baseDir, "src.txt"), []byte("test"), 0o600); err != nil {
+		t.Fatalf("cannot create source file: %s", err)
+	}
+
+	destDir := filepath.Join(t.TempDir(), "dest")
+	baseDirName := baseDir[len(srcDir):]
+
+	if err := CopyDir(srcDir, destDir, baseDirName); err != nil {
+		t.Fatalf("cannot copy directory: %s", err)
+	}
+
+	if _, err := os.Stat(filepath.Join(destDir, "work", "src.txt")); err != nil {
+		t.Fatalf("cannot stat copied source file: %s", err)
+	}
+}