diff --git a/hzulip.cabal b/hzulip.cabal
--- a/hzulip.cabal
+++ b/hzulip.cabal
@@ -1,5 +1,5 @@
 name:                hzulip
-version:             0.3.0.0
+version:             0.3.0.1
 synopsis:            A haskell wrapper for the Zulip API.
 description:         This a Zulip API wrapper for Haskell.
 homepage:            https://github.com/yamadapc/hzulip
@@ -15,12 +15,13 @@
 library
   exposed-modules:     HZulip
   other-modules:       HZulip.Types
-  build-depends:       base >=4.7 && <4.8
-                     , wreq >=0.2 && <0.3
-                     , lens >=4.4 && <4.5
-                     , aeson >=0.7 && <0.8
-                     , bytestring >=0.10 && <0.11
+  build-depends:       base >=4 && <5
+                     , wreq >=0.2 && <1
+                     , lens >=4.4 && <5
+                     , aeson >=0.7 && <1
+                     , bytestring >=0.10 && <1
                      , text >=1.1 &&<1.2
+                     , hspec >=1.11 && <2
   hs-source-dirs:      src
   default-language:    Haskell2010
 
@@ -29,11 +30,10 @@
   main-is:             Spec.hs
   hs-source-dirs:      src
                      , test
-  build-depends:       base >=4.7 && <4.8
-                     , wreq >=0.2 && <0.3
-                     , lens >=4.4 && <4.5
-                     , aeson >=0.7 && <0.8
-                     , bytestring >=0.10 && <0.11
-
-                     , hspec >=1.11 && <1.12
+  build-depends:       base >=4 && <5
+                     , wreq >=0.2 && <1
+                     , lens >=4.4 && <5
+                     , aeson >=0.7 && <1
+                     , bytestring >=0.10 && <1
+                     , hspec >=1.11 && <2
   default-language:    Haskell2010
diff --git a/src/HZulip.hs b/src/HZulip.hs
--- a/src/HZulip.hs
+++ b/src/HZulip.hs
@@ -5,6 +5,7 @@
               , User(..)
               , ZulipClient(..)
               , EventCallback
+              , MessageCallback
               , defaultBaseUrl
               , eventTypes
               , getEvents