diff --git a/wp-admin/includes/plugin.php b/wp-admin/includes/plugin.php
index 74345c41d6..b0341dcf6a 100644
--- a/wp-admin/includes/plugin.php
+++ b/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;
 		}
 	}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 0db37a10c5..012b1e72a3 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-alpha-37579';
+$wp_version = '4.6-alpha-37580';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.