diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 38771df..2e897bc 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         otp_version: [19.3.6, 20.3.8.26, 21.3.8.16, 22.3.4.2, 23.0.2]
-        os: [ubuntu-latest]
+        os: [ubuntu-18.04]
 
     steps:
     - uses: actions/checkout@v2
diff --git a/CHANGES.md b/CHANGES.md
index 633a8a9..4777f17 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,7 @@
+v3.1.0
+
+* Dialyzer and api spec improvements
+
 v3.0
 
 * drop support for OTP versions before 17.0
diff --git a/src/jsx.app.src b/src/jsx.app.src
index 52f6715..c4c28ab 100644
--- a/src/jsx.app.src
+++ b/src/jsx.app.src
@@ -1,7 +1,7 @@
 {application, jsx,
 [
     {description, "a streaming, evented json parsing toolkit"},
-    {vsn, "3.0.0"},
+    {vsn, "3.1.0"},
     {modules, [
         jsx,
         jsx_encoder,