diff --git a/src/wp-admin/includes/plugin.php b/src/wp-admin/includes/plugin.php
index 74345c41d6..b0341dcf6a 100644
--- a/src/wp-admin/includes/plugin.php
+++ b/src/wp-admin/includes/plugin.php
@@ -95,7 +95,7 @@ function get_plugin_data( $plugin_file, $markup = true, $translate = true ) {
 	// If no text domain is defined fall back to the plugin slug.
 	if ( ! $plugin_data['TextDomain'] ) {
 		$plugin_slug = dirname( plugin_basename( $plugin_file ) );
-		if ( '.' !== $plugin_slug && false === strpos( '/', $plugin_slug ) ) {
+		if ( '.' !== $plugin_slug && false === strpos( $plugin_slug, '/' ) ) {
 			$plugin_data['TextDomain'] = $plugin_slug;
 		}
 	}