diff --git a/CHANGELOG.md b/CHANGELOG.md
index f63acca..fe894eb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file.
 ## [Unreleased][unreleased]
 ### Fixed
 - Parse all dates as UTC to avoid timezone conversion errors
+- Use hapi-swagger 2.0.0, where the optional path parameter {format?} works as expected ([#32](https://github.com/metaodi/openerz/issues/32), thanks [Daniel Schregenberger](https://github.com/SuperBFG7))
 
 ## 0.11.0 - 2016-01-03
 ### Changed
diff --git a/package.json b/package.json
index 47b7c44..4edefce 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "fanci": "^0.5.0",
     "h2o2": "^4.0.2",
     "hapi": "^10.5.0",
-    "hapi-swagger": "^2.0.0",
+    "hapi-swagger": "2.0.0",
     "icalendar": "^0.7.1",
     "inert": "^3.2.0",
     "joi": "^7.0.1",