diff --git a/README.md b/README.md
index 73917db..e99704d 100644
--- a/README.md
+++ b/README.md
@@ -221,7 +221,8 @@ export WPT_PHP_EXECUTABLE=${WPT_PHP_EXECUTABLE-php}
 export WPT_PHPUNIT_CMD=""
 
 # (Optionally) define the command execution to remove the test directory
-# Use if `rm -r` can't be called directly for some reason.
+# Use if `rm -rf` can't be called directly for some reason. Include the `-f`
+# flag, or removal stops to ask about write-protected files such as git objects.
 export WPT_RM_TEST_DIR_CMD=""
 
 # SSH connection string (can also be an alias).
@@ -358,7 +359,7 @@ export WPT_PHPUNIT_CMD=""
 
 **Remove directory command**
 
-(Optionally) define the command execution to remove the test directory. Use if `rm -r` can't be called directly for some reason.
+(Optionally) define the command execution to remove the test directory. Use if `rm -rf` can't be called directly for some reason. Include the `-f` flag, or removal stops to ask about write-protected files such as git objects, and cleanup waits for input that never arrives.
 
 ```
 export WPT_RM_TEST_DIR_CMD=""
diff --git a/cleanup.php b/cleanup.php
index dddc5fb..ed09326 100644
--- a/cleanup.php
+++ b/cleanup.php
@@ -37,13 +37,13 @@
  * The following actions are performed:
  * - Forcefully deletes only the .git directory and the node_modules cache.
  * - Forcefully remove the `node_modules/.cache` directory.
- * - Remove the entire preparation directory.
+ * - Forcefully remove the entire preparation directory.
  */
 perform_operations(
 	array(
 		'rm -rf ' . escapeshellarg( $runner_vars['WPT_PREPARE_DIR'] . '/.git' ),
 		'rm -rf ' . escapeshellarg( $runner_vars['WPT_PREPARE_DIR'] . '/node_modules/.cache' ),
-		'rm -r ' . escapeshellarg( $runner_vars['WPT_PREPARE_DIR'] ),
+		'rm -rf ' . escapeshellarg( $runner_vars['WPT_PREPARE_DIR'] ),
 	)
 );
 
diff --git a/functions.php b/functions.php
index b8367c0..6291b48 100644
--- a/functions.php
+++ b/functions.php
@@ -87,7 +87,7 @@ function setup_runner_env_vars() {
 			'WPT_SSH_CONNECT'     => trim( getenv( 'WPT_SSH_CONNECT' ) ),
 			'WPT_SSH_OPTIONS'     => '' !== $ssh_options ? $ssh_options : '-o StrictHostKeyChecking=no',
 			'WPT_PHP_EXECUTABLE'  => '' !== $php_exec ? $php_exec : 'php',
-			'WPT_RM_TEST_DIR_CMD' => '' !== $rm_test_dir ? $rm_test_dir : 'rm -r ' . $runner_configuration['WPT_TEST_DIR'],
+			'WPT_RM_TEST_DIR_CMD' => '' !== $rm_test_dir ? $rm_test_dir : 'rm -rf ' . escapeshellarg( $runner_configuration['WPT_TEST_DIR'] ),
 			'WPT_REPORT_API_KEY'  => trim( getenv( 'WPT_REPORT_API_KEY' ) ),
 			'WPT_DEBUG'           => (bool) getenv( 'WPT_DEBUG' ),
 		)