diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 575ecf2..593bb97 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,11 @@ permissions: {}
 
 jobs:
   test:
-    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+    runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
diff --git a/fs_test.go b/fs_test.go
index 27e9875..65698e9 100644
--- a/fs_test.go
+++ b/fs_test.go
@@ -3,6 +3,7 @@ package clone
 import (
 	"os"
 	"path/filepath"
+	"runtime"
 	"testing"
 )
 
@@ -35,7 +36,7 @@ func TestCopyTreeCopiesFilesDirectoriesAndSymlinks(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if info.Mode().Perm() != 0o600 {
+	if runtime.GOOS != "windows" && info.Mode().Perm() != 0o600 {
 		t.Errorf("file mode = %o, want 600", info.Mode().Perm())
 	}
 	link, err := os.Readlink(filepath.Join(dst, "link"))
diff --git a/gogit/blob_test.go b/gogit/blob_test.go
index a099da9..d1bd8f3 100644
--- a/gogit/blob_test.go
+++ b/gogit/blob_test.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -280,7 +281,9 @@ func TestBlobPreservesGoGitAndGitErrors(t *testing.T) {
 	if !errors.Is(err, exec.ErrNotFound) {
 		t.Errorf("error = %v, want exec.ErrNotFound", err)
 	}
-	if err == nil || !strings.Contains(err.Error(), dir) {
+	// The go-git error renders the path with %q, so match the quoted
+	// form; on Windows the escaping doubles the backslashes.
+	if err == nil || !strings.Contains(err.Error(), fmt.Sprintf("%q", dir)) {
 		t.Errorf("error = %v, want starting path %q", err, dir)
 	}
 }
diff --git a/run_test.go b/run_test.go
index 6c309b6..a20d557 100644
--- a/run_test.go
+++ b/run_test.go
@@ -34,20 +34,22 @@ func TestRemoteEnv(t *testing.T) {
 func TestRunUsesDirectoryAndEnvironment(t *testing.T) {
 	requireGit(t)
 	dir := t.TempDir()
+	// A marker file read relative to the working directory proves dir is
+	// used without comparing path spellings, which differ under git's
+	// MSYS shell on Windows.
+	if err := os.WriteFile(filepath.Join(dir, "marker"), []byte("in-dir"), 0o644); err != nil {
+		t.Fatal(err)
+	}
 	out, err := Run(context.Background(), dir, []string{"CLONE_RUN_TEST=value"},
-		"-c", "alias.test=!pwd && printf \"|%s\" \"$CLONE_RUN_TEST\"", "test")
+		"-c", "alias.test=!cat marker && printf \"|%s\" \"$CLONE_RUN_TEST\"", "test")
 	if err != nil {
 		t.Fatalf("Run: %s: %v", out, err)
 	}
 	parts := strings.Split(strings.TrimSpace(out), "|")
-	resolvedDir, err := filepath.EvalSymlinks(dir)
-	if err != nil {
-		t.Fatal(err)
-	}
 	if len(parts) != 2 ||
-		strings.TrimSpace(parts[0]) != resolvedDir ||
+		strings.TrimSpace(parts[0]) != "in-dir" ||
 		strings.TrimSpace(parts[1]) != "value" {
-		t.Fatalf("Run output = %q, want %q and environment value", out, dir)
+		t.Fatalf("Run output = %q, want marker content and environment value", out)
 	}
 }
 
diff --git a/test_helpers_test.go b/test_helpers_test.go
index af10aa7..708ce99 100644
--- a/test_helpers_test.go
+++ b/test_helpers_test.go
@@ -7,6 +7,22 @@ import (
 	"testing"
 )
 
+// The library runs git with the ambient environment, so system and global
+// config (core.autocrlf=true on Windows runners) leaks into checkouts made
+// by the code under test. Isolate the whole test process, not just the
+// fixture helpers.
+func TestMain(m *testing.M) {
+	for key, value := range map[string]string{
+		"GIT_CONFIG_NOSYSTEM": "1",
+		"GIT_CONFIG_GLOBAL":   os.DevNull,
+	} {
+		if err := os.Setenv(key, value); err != nil {
+			panic(err)
+		}
+	}
+	os.Exit(m.Run())
+}
+
 func requireGit(t testing.TB) {
 	t.Helper()
 	if _, err := exec.LookPath("git"); err != nil {