diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7f98d64..0a9f699 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -29,7 +29,7 @@ jobs:
           ubuntu-18.04-clang-6.0,
           ubuntu-18.04-clang-7,
           ubuntu-18.04-clang-8,
-          ubuntu-18.04-clang-9,
+          ubuntu-20.04-clang-9,
           windows-2016-cl,
           windows-2016-clang-cl,
           windows-2016-clang,
@@ -111,8 +111,8 @@ jobs:
             compiler: clang
             version: "8"
 
-          - name: ubuntu-18.04-clang-9
-            os: ubuntu-18.04
+          - name: ubuntu-20.04-clang-9
+            os: ubuntu-20.04
             compiler: clang
             version: "9"
 
@@ -192,9 +192,9 @@ jobs:
           sudo add-apt-repository "deb http://dk.archive.ubuntu.com/ubuntu/ xenial universe"
           
           # LLVM 9 is not in Bionic's repositories so we add the official LLVM repository.
-          if [ "${{ matrix.compiler }}" = "clang" ] && [ "${{ matrix.version }}" = "9" ]; then
-            sudo add-apt-repository "deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main"
-          fi
+          #if [ "${{ matrix.compiler }}" = "clang" ] && [ "${{ matrix.version }}" = "9" ]; then
+          #  sudo add-apt-repository "deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main"
+          #fi
           sudo apt-get update
           # libc6-dbg:i386 is required for running valgrind on x86.
           sudo apt-get install -y ninja-build valgrind libc6-dbg:i386