diff --git a/src/controllers/topics.js b/src/controllers/topics.js
index 64db92ec08..b925568127 100644
--- a/src/controllers/topics.js
+++ b/src/controllers/topics.js
@@ -91,7 +91,7 @@ topicsController.get = function(req, res, next) {
 					postIndex = Math.max((req.params.post_index || 1) - (settings.postsPerPage + 1), 0);
 				}
 			} else if (!req.query.page) {
-				var index = Math.max(req.params.post_index - 1, 0);
+				var index = Math.max(req.params.post_index - 1, 0) || 0;
 				page = Math.max(1, Math.ceil(index / settings.postsPerPage));
 			}