diff --git a/Changelog.md b/Changelog.md
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,3 +1,7 @@
+## 1.2.14
+
+* Increased the upper-bound of `base` and `transformers`.
+
 ## 1.2.13
 
 * Increased the upper-bound of `aeson` to allow < 0.12.
diff --git a/engine-io.cabal b/engine-io.cabal
--- a/engine-io.cabal
+++ b/engine-io.cabal
@@ -1,5 +1,5 @@
 name: engine-io
-version: 1.2.13
+version: 1.2.14
 synopsis: A Haskell implementation of Engine.IO
 homepage: http://github.com/ocharles/engine.io
 license: BSD3
@@ -30,7 +30,7 @@
     aeson >=0.7 && <0.12,
     async >=2.0 && <2.2,
     attoparsec >=0.11 && <0.14,
-    base >=4.6 && <4.9,
+    base >=4.6 && <4.10,
     base64-bytestring >=1.0 && <1.1,
     bytestring >=0.10.2.0 && <0.11,
     either >= 3.4 && <4.5,
@@ -40,7 +40,7 @@
     stm >=2.4 && <2.5,
     stm-delay >= 0.1.1 && <0.2,
     text >=0.11 && <1.3,
-    transformers >=0.2 && <0.5,
+    transformers >=0.2 && <0.6,
     unordered-containers >=0.2 && <0.3,
     vector >=0.10 && <0.12,
     websockets >=0.8 && <0.10