diff --git a/.github/workflows/chest.yml b/.github/workflows/chest.yml
index 13d797c..2f8e759 100644
--- a/.github/workflows/chest.yml
+++ b/.github/workflows/chest.yml
@@ -23,7 +23,7 @@ jobs:
     strategy:
         matrix:
           os: [ ubuntu-latest ]
-          smalltalk: [ Pharo64-12 ]
+          smalltalk: [ Pharo64-13 ]
     runs-on: ${{ matrix.os }}
     name: ${{ matrix.smalltalk }} on ${{ matrix.os }}
     steps: