diff --git a/includes/CLI/Plugin_Check_Command.php b/includes/CLI/Plugin_Check_Command.php
index 4e1e28d32..ee0ff7fe4 100644
--- a/includes/CLI/Plugin_Check_Command.php
+++ b/includes/CLI/Plugin_Check_Command.php
@@ -40,6 +40,20 @@ final class Plugin_Check_Command {
 		'json',
 	);
 
+	/**
+	 * Field names.
+	 *
+	 * @since n.e.x.t
+	 * @var string[]
+	 */
+	protected $allowed_fields = array(
+		'line',
+		'column',
+		'type',
+		'code',
+		'message',
+	);
+
 	/**
 	 * Constructor.
 	 *
@@ -114,21 +128,12 @@ public function __construct( Plugin_Context $plugin_context ) {
 	 * @SuppressWarnings(PHPMD.ExcessiveMethodLength)
 	 */
 	public function check( $args, $assoc_args ) {
-		/*
-		 * Bail early if the Plugin Checker is not activated.
-		 *
-		 * If the Plugin Checker is not activated, it will throw an error and
-		 * CLI commands won't be usable.
-		 */
-		if ( is_plugin_inactive( $this->plugin_context->basename() ) ) {
-			WP_CLI::error(
-				__( 'Plugin Checker is not active.', 'plugin-check' )
-			);
-		}
-
 		// Get options based on the CLI arguments.
 		$options = $this->get_options( $assoc_args );
 
+		// Validate field names.
+		$this->validate_fields( wp_parse_list( $options['fields'] ) );
+
 		// Create the plugin and checks array from CLI arguments.
 		$plugin = isset( $args[0] ) ? $args[0] : '';
 		$checks = wp_parse_list( $options['checks'] );
@@ -411,4 +416,21 @@ private function has_runtime_check( array $checks ) {
 
 		return false;
 	}
+
+	/**
+	 * Validate field names.
+	 *
+	 * @since n.e.x.t
+	 *
+	 * @param array $fields An array of field names.
+	 */
+	private function validate_fields( array $fields ) {
+		$invalid_fields = array_diff( $fields, $this->allowed_fields );
+
+		if ( count( $invalid_fields ) > 0 ) {
+			// translators: %s: Field names.
+			$message = ( 1 === count( $invalid_fields ) ) ? __( 'Invalid field: %s', 'plugin-check' ) : __( 'Invalid fields: %s', 'plugin-check' );
+			WP_CLI::error( sprintf( $message, join( ', ', $invalid_fields ) ) );
+		}
+	}
 }