diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,9 @@
 # Revision history for greskell-websocket
 
+## 0.1.2.6  -- 2021-11-08
+
+* Confirm test with `base-4.15.0.0`
+
 ## 0.1.2.5  -- 2020-12-30
 
 * Confirm test with `base64-bytestring-1.2.0.0`
diff --git a/greskell-websocket.cabal b/greskell-websocket.cabal
--- a/greskell-websocket.cabal
+++ b/greskell-websocket.cabal
@@ -1,5 +1,5 @@
 name:                   greskell-websocket
-version:                0.1.2.5
+version:                0.1.2.6
 author:                 Toshio Ito <debug.ito@gmail.com>
 maintainer:             Toshio Ito <debug.ito@gmail.com>
 license:                BSD3
@@ -43,7 +43,7 @@
                         Network.Greskell.WebSocket.Connection.Type,
                         Network.Greskell.WebSocket.Client.Impl,
                         Network.Greskell.WebSocket.Util
-  build-depends:        base >=4.9.1.0 && <4.15,
+  build-depends:        base >=4.9.1.0 && <4.16,
                         greskell-core >=0.1.2.0 && <0.2,
                         bytestring >=0.10.8.1 && <0.11,
                         base64-bytestring >=1.0.0.1 && <1.3,
@@ -78,6 +78,7 @@
   other-extensions:     OverloadedStrings, DuplicateRecordFields,
                         NoMonomorphismRestriction
   other-modules:        Network.Greskell.WebSocket.Codec.JSONSpec
+  build-tool-depends:   hspec-discover:hspec-discover
   build-depends:        base, greskell-websocket, aeson, uuid, bytestring, unordered-containers, vector, greskell-core,
                         hspec >=2.4.4