diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8652318..a9c8135 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,4 +61,4 @@ jobs:
         with:
           fetch-depth: 0
       - uses: olafurpg/setup-scala@v13
-      - run: sbt '++2.12.18; docs/mdoc'
+      - run: sbt '++2.13.15; docs/mdoc'