diff --git a/.github/workflows/multi_ver_unittest.yml b/.github/workflows/multi_ver_unittest.yml
index d281645..2f3f1e6 100644
--- a/.github/workflows/multi_ver_unittest.yml
+++ b/.github/workflows/multi_ver_unittest.yml
@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: ["1.18", "1.20"]
+        go-version: ["1.18", "1.21"]
     steps:
       - uses: actions/checkout@v4
       - name: Setup Go ${{ matrix.go-version }}
diff --git a/go.mod b/go.mod
index e3d9424..fa35d60 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module github.com/go-spectest/markdown
 
-go 1.21.1
+go 1.18