Index: wp-includes/capabilities.php
===================================================================
--- wp-includes/capabilities.php	(revision 1218)
+++ wp-includes/capabilities.php	(working copy)
@@ -534,9 +534,9 @@
 		$this->allcaps = array();
 		foreach ( (array) $this->roles as $role ) {
 			$role =& $wp_roles->get_role( $role );
-			$this->allcaps = array_merge( $this->allcaps, $role->capabilities );
+			$this->allcaps = array_merge( (array) $this->allcaps, (array) $role->capabilities );
 		}
-		$this->allcaps = array_merge( $this->allcaps, $this->caps );
+		$this->allcaps = array_merge( (array) $this->allcaps, (array) $this->caps );
 	}
 
 	/**