diff --git a/.github/workflows/pull_request.yaml b/.github/workflows/pull_request.yaml
index 19a693b..f69ba5a 100644
--- a/.github/workflows/pull_request.yaml
+++ b/.github/workflows/pull_request.yaml
@@ -32,4 +32,4 @@ jobs:
   test_library:
     uses: NWChemEx/.github/.github/workflows/test_nwx_library.yaml@master
     with:
-      compilers: '["gcc-14", "clang-19"]'
+      compilers: '["gcc-14", "clang-18"]'
diff --git a/.github/workflows/run_tests_on_master.yaml b/.github/workflows/run_tests_on_master.yaml
index 3c4a56b..22260c9 100644
--- a/.github/workflows/run_tests_on_master.yaml
+++ b/.github/workflows/run_tests_on_master.yaml
@@ -22,4 +22,4 @@ jobs:
   test_library:
     uses: NWChemEx/.github/.github/workflows/test_nwx_library.yaml@master
     with:
-      compilers: '["gcc-14", "clang-19"]'
+      compilers: '["gcc-14", "clang-18"]'