diff --git a/.github/codeql/codeql-config.yml b/.github/codeql/codeql-config.yml
new file mode 100644
index 0000000000..7196708b21
--- /dev/null
+++ b/.github/codeql/codeql-config.yml
@@ -0,0 +1,4 @@
+name: "CodeQL config for the Ruby language"
+
+paths-ignore:
+  - '/ext/**/*/conftest.c'
diff --git a/.github/workflows/codeql-analysis.yml b/.github/workflows/codeql-analysis.yml
index b571409abf..bee79cb1ab 100644
--- a/.github/workflows/codeql-analysis.yml
+++ b/.github/workflows/codeql-analysis.yml
@@ -31,6 +31,7 @@ jobs:
       uses: github/codeql-action/init@v1
       with:
         languages: cpp
+        config-file: ./.github/codeql/codeql-config.yml
 
     - name: Autobuild
       uses: github/codeql-action/autobuild@v1