diff --git a/.gitignore b/.gitignore
index b1b4744..0d625e5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ package-lock.json
 yarn.lock
 pnpm-lock.yaml
 logs
+test-convert-logs
 tmp/
 testing/
 .claude/settings.local.json
diff --git a/src/logger.ts b/src/logger.ts
index 151e0ae..81078c2 100644
--- a/src/logger.ts
+++ b/src/logger.ts
@@ -38,6 +38,10 @@ function appendToLogFile(filePath: string, entry: unknown) {
 	try {
 		const logPath = getLogPath();
 		confirmOrCreateFolder(logPath);
+
+		// Sanitize file name for Windows compatibility
+		filePath = filePath.replace(/:/g, '-');
+
 		const fullPath = `${logPath}/${filePath}`;
 
 		// Use synchronous append to ensure immediate write
diff --git a/src/migrate/cli.ts b/src/migrate/cli.ts
index 4d6b237..de66397 100644
--- a/src/migrate/cli.ts
+++ b/src/migrate/cli.ts
@@ -1285,7 +1285,8 @@ export async function runCLI(cliArgs?: CLIArgs) {
 	// Use CLI args as initial values if provided
 	const initialTransformer =
 		cliArgs?.transformer || savedSettings.key || transformers[0].key;
-	const initialFile = cliArgs?.file || savedSettings.file || 'users.json';
+	const initialFile =
+		cliArgs?.file || savedSettings.file || 'samples/clerk.csv';
 	const initialResumeAfter = cliArgs?.resumeAfter || '';
 
 	const initialArgs = await p.group(
diff --git a/tests/convert-logs.test.ts b/tests/convert-logs.test.ts
index b4985fc..28e9b74 100644
--- a/tests/convert-logs.test.ts
+++ b/tests/convert-logs.test.ts
@@ -8,7 +8,8 @@ import {
 } from 'node:fs';
 import path from 'node:path';
 
-const LOGS_DIR = path.join(process.cwd(), 'logs');
+// Use a unique directory to avoid conflicts with logger.test.ts which also uses 'logs/'
+const LOGS_DIR = path.join(process.cwd(), 'test-convert-logs');
 
 // Helper to clean up logs directory
 const cleanupLogs = () => {
diff --git a/tests/logger.test.ts b/tests/logger.test.ts
index 7e3bb2f..e775596 100644
--- a/tests/logger.test.ts
+++ b/tests/logger.test.ts
@@ -7,13 +7,29 @@ import {
 	importLogger,
 	validationLogger,
 } from '../src/logger';
-import { existsSync, readFileSync, rmSync } from 'node:fs';
+import { existsSync, readdirSync, readFileSync, unlinkSync } from 'node:fs';
 
-// Helper to clean up logs directory
-const cleanupLogs = () => {
-	closeAllStreams(); // Close streams before cleanup
+// Snapshot of files in logs/ before each test so we only clean up test-created files
+let existingLogFiles: Set<string> = new Set();
+
+// Capture which files already exist before a test runs
+const snapshotExistingLogs = () => {
+	closeAllStreams();
 	if (existsSync('logs')) {
-		rmSync('logs', { recursive: true });
+		existingLogFiles = new Set(readdirSync('logs'));
+	} else {
+		existingLogFiles = new Set();
+	}
+};
+
+// Only remove files created by the test, never delete the logs/ directory
+const cleanupTestLogs = () => {
+	closeAllStreams();
+	if (!existsSync('logs')) return;
+	for (const file of readdirSync('logs')) {
+		if (!existingLogFiles.has(file)) {
+			unlinkSync(`logs/${file}`);
+		}
 	}
 };
 
@@ -28,8 +44,8 @@ const readNDJSON = (filePath: string): Record<string, unknown>[] => {
 };
 
 describe('errorLogger', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('logs a single error to migration log', () => {
 		const dateTime = 'error-single-test';
@@ -169,8 +185,8 @@ describe('errorLogger', () => {
 });
 
 describe('validationLogger', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('logs a validation error to migration log', () => {
 		const dateTime = 'validation-basic-test';
@@ -279,8 +295,8 @@ describe('validationLogger', () => {
 });
 
 describe('importLogger', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('logs a successful import', () => {
 		const dateTime = 'import-success-test';
@@ -351,8 +367,8 @@ describe('importLogger', () => {
 });
 
 describe('deleteErrorLogger', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('logs a single error to user deletion log', () => {
 		const dateTime = 'delete-error-single-test';
@@ -468,8 +484,8 @@ describe('deleteErrorLogger', () => {
 });
 
 describe('deleteLogger', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('logs a successful deletion', () => {
 		const dateTime = 'delete-success-test';
@@ -524,8 +540,8 @@ describe('deleteLogger', () => {
 });
 
 describe('mixed logging', () => {
-	beforeEach(cleanupLogs);
-	afterEach(cleanupLogs);
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
 
 	test('error and validation logs go to same migration log file', () => {
 		const dateTime = 'mixed-errors-test';
@@ -593,3 +609,27 @@ describe('mixed logging', () => {
 		expect(migrationLog[2].clerkUserId).toBe('clerk_2');
 	});
 });
+
+describe('filename sanitization', () => {
+	beforeEach(snapshotExistingLogs);
+	afterEach(cleanupTestLogs);
+
+	test('replaces colons with hyphens in log filenames for Windows compatibility', () => {
+		const dateTime = '2026-01-20T14:30:45';
+
+		importLogger(
+			{ userId: 'user_1', status: 'success', clerkUserId: 'clerk_1' },
+			dateTime
+		);
+
+		const sanitizedFileName = 'migration-2026-01-20T14-30-45.log';
+		const log = readNDJSON(`logs/${sanitizedFileName}`);
+		expect(log).toHaveLength(1);
+		expect(log[0].userId).toBe('user_1');
+
+		// Verify no file with colons was created
+		const logFiles = readdirSync('logs');
+		expect(logFiles).not.toContain('migration-2026-01-20T14:30:45.log');
+		expect(logFiles).toContain(sanitizedFileName);
+	});
+});
diff --git a/tests/migrate/functions.test.ts b/tests/migrate/functions.test.ts
index 8be83b4..388adec 100644
--- a/tests/migrate/functions.test.ts
+++ b/tests/migrate/functions.test.ts
@@ -1,8 +1,32 @@
-import { describe, expect, test } from 'vitest';
+import { afterEach, beforeEach, describe, expect, test } from 'vitest';
+import { existsSync, readdirSync, unlinkSync } from 'node:fs';
 import { loadUsersFromFile } from '../../src/migrate/functions';
 import { transformKeys } from '../../src/utils';
 import { transformers } from '../../src/transformers';
 
+// Snapshot of files in logs/ before each test so we only clean up test-created files
+let existingLogFiles: Set<string> = new Set();
+
+const snapshotExistingLogs = () => {
+	if (existsSync('logs')) {
+		existingLogFiles = new Set(readdirSync('logs'));
+	} else {
+		existingLogFiles = new Set();
+	}
+};
+
+const cleanupTestLogs = () => {
+	if (!existsSync('logs')) return;
+	for (const file of readdirSync('logs')) {
+		if (!existingLogFiles.has(file)) {
+			unlinkSync(`logs/${file}`);
+		}
+	}
+};
+
+beforeEach(snapshotExistingLogs);
+afterEach(cleanupTestLogs);
+
 test('Clerk - loadUsersFromFile - JSON', async () => {
 	const { users: usersFromClerk } = await loadUsersFromFile(
 		'./samples/clerk.json',
diff --git a/tests/migrate/import-users.test.ts b/tests/migrate/import-users.test.ts
index bd1d3a7..28f3e9c 100644
--- a/tests/migrate/import-users.test.ts
+++ b/tests/migrate/import-users.test.ts
@@ -1,6 +1,4 @@
-import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest';
-import { existsSync, rmSync } from 'node:fs';
-
+import { beforeEach, describe, expect, test, vi } from 'vitest';
 // Mock @clerk/backend before importing the module
 const mockCreateUser = vi.fn();
 const mockCreateEmailAddress = vi.fn();
@@ -100,21 +98,9 @@ import {
 } from '../../src/migrate/import-users';
 import * as logger from '../../src/logger';
 
-// Helper to clean up logs directory
-const cleanupLogs = () => {
-	if (existsSync('logs')) {
-		rmSync('logs', { recursive: true, force: true, maxRetries: 3 });
-	}
-};
-
 describe('importUsers', () => {
 	beforeEach(() => {
 		vi.clearAllMocks();
-		cleanupLogs();
-	});
-
-	afterEach(() => {
-		cleanupLogs();
 	});
 
 	describe('createUser API calls', () => {
@@ -405,11 +391,6 @@ describe('importUsers edge cases', () => {
 	beforeEach(() => {
 		vi.clearAllMocks();
 		mockCreatePhoneNumber.mockReset();
-		cleanupLogs();
-	});
-
-	afterEach(() => {
-		cleanupLogs();
 	});
 
 	test('handles empty user array', async () => {