diff --git a/.github/workflows/rust_custom_mutator.yml b/.github/workflows/rust_custom_mutator.yml
index 7c2f0c12..f5c16a1e 100644
--- a/.github/workflows/rust_custom_mutator.yml
+++ b/.github/workflows/rust_custom_mutator.yml
@@ -18,7 +18,7 @@ jobs:
         working-directory: custom_mutators/rust
     strategy:
       matrix:
-        os: [ubuntu-22.04, ubuntu-20.04]
+        os: [ubuntu-22.04]
     steps:
       - uses: actions/checkout@v3
       - name: Install Rust Toolchain