Index: src/bp-templates/bp-legacy/buddypress-functions.php
===================================================================
--- src/bp-templates/bp-legacy/buddypress-functions.php
+++ src/bp-templates/bp-legacy/buddypress-functions.php
@@ -793,10 +793,10 @@
 		// determine depth
 		$depth = 1;
 		$parent_id = $activities_template->activities[0]->secondary_item_id;
-		while ( $parent_id !== $activities_template->activities[0]->item_id ) {
+		while ( $parent_id !== (int) $activities_template->activities[0]->item_id ) {
 			$depth++;
 			$p_obj = new BP_Activity_Activity( $parent_id );
-			$parent_id = $p_obj->secondary_item_id;
+			$parent_id = (int) $p_obj->secondary_item_id;
 		}
 		$activities_template->activity->current_comment->depth = $depth;
 	}