diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7ee9b494..25e9ead1a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,11 @@
 **Note**: A feature tagged as Experimental is in a
 high state of flux, you're at risk of it changing without notice.
 
+# 2.10.4
+
+- **Bug Fix**
+  - `altW` left type is too wide in `Either`-based data types, #1488 (@wmaurer)
+
 # 2.10.3
 
 - **Bug Fix**
diff --git a/package.json b/package.json
index 42ae436c7..ac6069ba5 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "fp-ts",
-  "version": "2.10.3",
+  "version": "2.10.4",
   "description": "Functional programming in TypeScript",
   "main": "lib/index.js",
   "module": "es6/index.js",