diff --git a/tests/test_streaming_client.py b/tests/test_streaming_client.py
index 9f636d9..2929441 100644
--- a/tests/test_streaming_client.py
+++ b/tests/test_streaming_client.py
@@ -633,21 +633,28 @@ assert '"Second"' in stdin_messages[1]
 print('{"type": "result", "subtype": "success", "duration_ms": 100, "duration_api_ms": 50, "is_error": false, "num_turns": 1, "session_id": "test", "total_cost_usd": 0.001}')
 """)
 
-            Path(test_script).chmod(0o755)
+            # Make script executable (Unix-style systems)
+            if sys.platform != "win32":
+                Path(test_script).chmod(0o755)
 
             try:
-                # Mock _find_cli to return python executing our test script
+                # Mock _find_cli to return the test script path directly
                 with patch.object(
-                    SubprocessCLITransport, "_find_cli", return_value=sys.executable
+                    SubprocessCLITransport, "_find_cli", return_value=test_script
                 ):
-                    # Mock _build_command to add our test script as first argument
+                    # Mock _build_command to properly execute Python script
                     original_build_command = SubprocessCLITransport._build_command
 
                     def mock_build_command(self):
                         # Get original command
                         cmd = original_build_command(self)
-                        # Replace the CLI path with python + script
-                        cmd[0] = test_script
+                        # On Windows, we need to use python interpreter to run the script
+                        if sys.platform == "win32":
+                            # Replace first element with python interpreter and script
+                            cmd[0:1] = [sys.executable, test_script]
+                        else:
+                            # On Unix, just use the script directly
+                            cmd[0] = test_script
                         return cmd
 
                     with patch.object(
diff --git a/tests/test_transport.py b/tests/test_transport.py
index f46a2ea..93538f4 100644
--- a/tests/test_transport.py
+++ b/tests/test_transport.py
@@ -44,13 +44,15 @@ class TestSubprocessCLITransport:
         """Test that cli_path accepts pathlib.Path objects."""
         from pathlib import Path
 
+        path = Path("/usr/bin/claude")
         transport = SubprocessCLITransport(
             prompt="Hello",
             options=ClaudeAgentOptions(),
-            cli_path=Path("/usr/bin/claude"),
+            cli_path=path,
         )
 
-        assert transport._cli_path == "/usr/bin/claude"
+        # Path object is converted to string, compare with str(path)
+        assert transport._cli_path == str(path)
 
     def test_build_command_with_system_prompt_string(self):
         """Test building CLI command with system prompt as string."""
@@ -129,19 +131,25 @@ class TestSubprocessCLITransport:
         """Test building CLI command with add_dirs option."""
         from pathlib import Path
 
+        dir1 = "/path/to/dir1"
+        dir2 = Path("/path/to/dir2")
         transport = SubprocessCLITransport(
             prompt="test",
-            options=ClaudeAgentOptions(
-                add_dirs=["/path/to/dir1", Path("/path/to/dir2")]
-            ),
+            options=ClaudeAgentOptions(add_dirs=[dir1, dir2]),
             cli_path="/usr/bin/claude",
         )
 
         cmd = transport._build_command()
-        cmd_str = " ".join(cmd)
 
-        # Check that the command string contains the expected --add-dir flags
-        assert "--add-dir /path/to/dir1 --add-dir /path/to/dir2" in cmd_str
+        # Check that both directories are in the command
+        assert "--add-dir" in cmd
+        add_dir_indices = [i for i, x in enumerate(cmd) if x == "--add-dir"]
+        assert len(add_dir_indices) == 2
+
+        # The directories should appear after --add-dir flags
+        dirs_in_cmd = [cmd[i + 1] for i in add_dir_indices]
+        assert dir1 in dirs_in_cmd
+        assert str(dir2) in dirs_in_cmd
 
     def test_session_continuation(self):
         """Test session continuation options."""
@@ -322,28 +330,31 @@ class TestSubprocessCLITransport:
         from pathlib import Path
 
         # Test with string path
+        string_path = "/path/to/mcp-config.json"
         transport = SubprocessCLITransport(
             prompt="test",
-            options=ClaudeAgentOptions(mcp_servers="/path/to/mcp-config.json"),
+            options=ClaudeAgentOptions(mcp_servers=string_path),
             cli_path="/usr/bin/claude",
         )
 
         cmd = transport._build_command()
         assert "--mcp-config" in cmd
         mcp_idx = cmd.index("--mcp-config")
-        assert cmd[mcp_idx + 1] == "/path/to/mcp-config.json"
+        assert cmd[mcp_idx + 1] == string_path
 
         # Test with Path object
+        path_obj = Path("/path/to/mcp-config.json")
         transport = SubprocessCLITransport(
             prompt="test",
-            options=ClaudeAgentOptions(mcp_servers=Path("/path/to/mcp-config.json")),
+            options=ClaudeAgentOptions(mcp_servers=path_obj),
             cli_path="/usr/bin/claude",
         )
 
         cmd = transport._build_command()
         assert "--mcp-config" in cmd
         mcp_idx = cmd.index("--mcp-config")
-        assert cmd[mcp_idx + 1] == "/path/to/mcp-config.json"
+        # Path object gets converted to string, compare with str(path_obj)
+        assert cmd[mcp_idx + 1] == str(path_obj)
 
     def test_build_command_with_mcp_servers_as_json_string(self):
         """Test building CLI command with mcp_servers as JSON string."""