diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 ## Changelog for the `threepenny-gui` package
 
+**0.6.0.5** -- Maintenance release
+
+* Bump `async` dependency to allow 2.1
+* Bump `transformers` dependency to allow 0.5
+
 **0.6.0.4** -- Maintenance release.
 
 * Elements that have become unreachable, for instance because they have been removed from the DOM and are no longer reachable in the Haskell code, will be garbage collected again. Fix [#109][], [#113][].
diff --git a/threepenny-gui.cabal b/threepenny-gui.cabal
--- a/threepenny-gui.cabal
+++ b/threepenny-gui.cabal
@@ -1,5 +1,5 @@
 Name:                threepenny-gui
-Version:             0.6.0.4
+Version:             0.6.0.5
 Synopsis:            GUI framework that uses the web browser as a display.
 Description:
     Threepenny-GUI is a GUI framework that uses the web browser as a display.
@@ -105,7 +105,7 @@
       ghc-options:  -O2 -threaded
   build-depends:     base                   >= 4.6   && < 4.9
                     ,aeson                  >= 0.7   && < 0.11
-                    ,async                  == 2.0.*
+                    ,async                  >= 2.0   && < 2.2
                     ,bytestring             >= 0.9.2 && < 0.11
                     ,containers             >= 0.4.2 && < 0.6
                     ,data-default           == 0.5.*
@@ -118,7 +118,7 @@
                     ,stm                    >= 2.2    && < 2.5
                     ,template-haskell       >= 2.7.0  && < 2.11
                     ,text                   >= 0.11   && < 1.3
-                    ,transformers           >= 0.3.0  && < 0.5
+                    ,transformers           >= 0.3.0  && < 0.6
                     ,unordered-containers   == 0.2.*
                     ,websockets             >= 0.8    && < 0.10
                     ,websockets-snap        >= 0.8    && < 0.10