diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4c67af3..89c671e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,7 +13,7 @@ jobs:
   rustfmt_check:
     strategy:
       matrix:
-        os: [macos-latest, windows-latest, ubuntu-latest]
+        os: [macos-latest, windows-latest, ubuntu-20.04]
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:
@@ -134,7 +134,7 @@ jobs:
       - name: Install valgrind dependencies
         # On Debian, Ubuntu libc6-dbg is required for valgrind
         run: |
-          sudo apt-get -y install libc6-dbg=2.35-0ubuntu3.6
+          sudo apt-get -y install libc6-dbg
           cargo install cargo-valgrind --version 2.0.2
 
       - name: Cache valgrind