diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 29ea90f4..0b0464db 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -132,9 +132,10 @@ jobs:
             CC_INNER_LOOP: "gcc"
             INSTALL_OPENCV: "true"
 
+          # Pin the Clang 18 jobs to Ubuntu 24.04 for its LLVM 18 packages.
           # Linux + Python 3.10 and homogeneous runtime nesting.
           - name: py310_conda_openblas_clang_clang
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PACKAGER: "conda"
             PYTHON_VERSION: "3.10"
             BLAS: "openblas"
@@ -145,7 +146,7 @@ jobs:
           # Linux environment with MKL and Clang (known to be unsafe for
           # threadpoolctl) to only test the warning from multiple OpenMP.
           - name: pylatest_conda_mkl_clang_gcc
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PYTHON_VERSION: "*"
             PACKAGER: "conda"
             BLAS: "mkl"
@@ -166,7 +167,7 @@ jobs:
           # Linux + Python 3.11 with numpy / scipy installed with pip from PyPI
           # and heterogeneous OpenMP runtimes.
           - name: py311_pip_openblas_gcc_clang
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PACKAGER: "pip"
             PYTHON_VERSION: "3.11"
             CC_OUTER_LOOP: "gcc"
@@ -207,7 +208,7 @@ jobs:
             CC_INNER_LOOP: "gcc"
           # Linux environment with no numpy and heterogeneous OpenMP runtimes.
           - name: pylatest_conda_nonumpy_gcc_clang
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PACKAGER: "conda"
             PYTHON_VERSION: "*"
             NO_NUMPY: "true"
@@ -216,7 +217,7 @@ jobs:
 
           # Linux environments with numpy linked to BLIS
           - name: pylatest_blis_gcc_clang_openmp
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PYTHON_VERSION: "*"
             INSTALL_BLAS: "blis"
             BLIS_NUM_THREAEDS: "4"
@@ -225,7 +226,7 @@ jobs:
             BLIS_CC: "clang-18"
             BLIS_ENABLE_THREADING: "openmp"
           - name: pylatest_blis_clang_gcc_pthreads
-            os: ubuntu-latest
+            os: ubuntu-24.04
             PYTHON_VERSION: "*"
             INSTALL_BLAS: "blis"
             BLIS_NUM_THREADS: "4"
diff --git a/continuous_integration/install.sh b/continuous_integration/install.sh
index 01190bdb..5592ff09 100755
--- a/continuous_integration/install.sh
+++ b/continuous_integration/install.sh
@@ -7,16 +7,13 @@ set -xe
 UNAMESTR=`uname`
 
 
-# Install a recent version of clang and libomp if needed
-# Only applicable to linux jobs
+# Install the matching Clang and OpenMP packages from Ubuntu 24.04.
 if [[ "$CC_OUTER_LOOP" == "clang-18" ]] || \
    [[ "$CC_INNER_LOOP" == "clang-18" ]] || \
    [[ "$BLIS_CC" == "clang-18" ]]
 then
-    wget https://apt.llvm.org/llvm.sh
-    chmod +x llvm.sh
-    sudo ./llvm.sh 18
-    sudo apt-get install libomp-dev
+    sudo apt-get update
+    sudo apt-get install -y clang-18 libomp-18-dev
 fi