diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
new file mode 100644
index 0000000..d42e775
--- /dev/null
+++ b/.github/workflows/build.yml
@@ -0,0 +1,31 @@
+name: CI
+
+env:
+  GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+# Controls when the action will run. Triggers the workflow on push or pull request
+# events but only for the development branch
+on:
+  pull_request:
+    types: [assigned, opened, synchronize, reopened]
+    
+  push:
+    branches:
+      - main
+  
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        pharoversion: [ Pharo64-14, Pharo64-13, Pharo64-12 ]
+    name: ${{ matrix.pharoversion }}
+    steps:
+      - uses: actions/checkout@v2
+      - uses: hpi-swa/setup-smalltalkCI@v1
+        id: smalltalkci
+        with:
+          smalltalk-version: ${{ matrix.pharoversion }}
+      - run: smalltalkci -s ${{  steps.smalltalkci.outputs.smalltalk-version}}
+        shell: bash
+        timeout-minutes: 15
diff --git a/.smalltalk.ston b/.smalltalk.ston
new file mode 100644
index 0000000..96410b5
--- /dev/null
+++ b/.smalltalk.ston
@@ -0,0 +1,9 @@
+SmalltalkCISpec {
+  #loading : [
+    SCIMetacelloLoadSpec {
+      #baseline : 'RecurringEvents',
+      #directory : 'source',
+      #platforms : [ #pharo ]
+    }
+  ]
+}
diff --git a/source/RecurringEvents-Core/RETemporalExpression.class.st b/source/RecurringEvents-Core/RETemporalExpression.class.st
index a7cba23..afd236a 100644
--- a/source/RecurringEvents-Core/RETemporalExpression.class.st
+++ b/source/RecurringEvents-Core/RETemporalExpression.class.st
@@ -161,7 +161,7 @@ RETemporalExpression class >> fromJsonDict: aDict [
 
 { #category : 'json' }
 RETemporalExpression class >> fromJsonString: aString [
-	^ self fromJsonDict: (NeoJSONReader fromString: aString)
+	^ self fromJsonDict: (STONJSON fromString: aString)
 ]
 
 { #category : 'rrule' }
@@ -509,7 +509,7 @@ RETemporalExpression >> asJsonDict [
 
 { #category : 'json' }
 RETemporalExpression >> asJsonString [
-	^ NeoJSONWriter toString: self asJsonDict
+	^ STONJSON toString: self asJsonDict
 ]
 
 { #category : 'rrule' }