diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c4dbae0..e709352 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -42,6 +42,6 @@ jobs:
           go-version: ${{ matrix.go }}
           cache: true
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v8
+        uses: golangci/golangci-lint-action@v9
         with:
           version: ${{ matrix.lint }}
diff --git a/client.go b/client.go
index 07eb1dd..8aae299 100644
--- a/client.go
+++ b/client.go
@@ -326,5 +326,5 @@ func rawResponseFromErr(err error) []byte {
 	}
 
 	// if the error is not an HTTPError return instead the error's details
-	return []byte(fmt.Sprintf("%v", err))
+	return fmt.Appendf(nil, "%v", err)
 }
diff --git a/retry/exp_backoff_test.go b/retry/exp_backoff_test.go
index a94d0bf..71e8a0a 100644
--- a/retry/exp_backoff_test.go
+++ b/retry/exp_backoff_test.go
@@ -1,5 +1,4 @@
 //go:build integrationtest || !unittest
-// +build integrationtest !unittest
 
 package retry_test