diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 9a0bd1b..06cc60a 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        go-version: [ oldstable, stable ]
+        go-version: [ 1.18.x, oldstable, stable ]
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
diff --git a/README.md b/README.md
index 4361613..21f4d3e 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ For `Connect` see [connectrpc/validate-go](https://github.com/connectrpc/validat
 
 ## Installation
 
-**Requires the `go` toolchain (≥ v1.19)**
+**Requires the `go` toolchain (≥ v1.18)**
 
 To install the package, use the `go get` command from within your Go module: