diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# Version 1.3.4
+
+* Fix typo in `unliftio-core` Cabal flag.
+
+
 # Version 1.3.3
 
 * Add `MonadBase`, `MonadBaseControl`, `PrimMonad` and `MonadSafe` instances
diff --git a/di-monad.cabal b/di-monad.cabal
--- a/di-monad.cabal
+++ b/di-monad.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.18
 name: di-monad
-version: 1.3.3
+version: 1.3.4
 author: Renzo Carbonara
 maintainer: renλren.zone
 copyright: Renzo Carbonara 2017-2018
@@ -90,6 +90,6 @@
     build-depends: transformers-base
 
   if flag(unliftio-core)
-    cpp-options: -DFLAG_unliftio-core
+    cpp-options: -DFLAG_unliftio_core
     build-depends: unliftio-core