diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 93112d9b..421c95de 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -36,6 +36,12 @@ jobs:
       matrix: #using macos-15-intel, last available intel architecture. macos-latest is arm64 architecture.
         os: [macos-15-intel, windows-latest, ubuntu-latest, macos-latest]
         python-version: ['3.9', '3.12']
+        # Combination of old architecture, macos-intel, and new python, 3.12, causes issues:
+        # llvmlite is not available for this combination from PyPI so skip that testing.
+        # It is available from conda-forge so not completely unsupported.
+        exclude:
+          - os: macos-15-intel
+            python-version: '3.12'
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v5
diff --git a/.github/workflows/scheduled_or_manual.yml b/.github/workflows/scheduled_or_manual.yml
index fc48b55b..92647f2e 100644
--- a/.github/workflows/scheduled_or_manual.yml
+++ b/.github/workflows/scheduled_or_manual.yml
@@ -37,6 +37,12 @@ jobs:
       matrix: #using macos-15-intel, last available intel architecture. macos-latest is arm64 architecture.
         os: [macos-15-intel, windows-latest, macos-latest]
         python-version: ['3.9', '3.12']
+        # Combination of old architecture, macos-intel, and new python, 3.12, causes issues:
+        # llvmlite is not available for this combination from PyPI so skip that testing.
+        # It is available from conda-forge so not completely unsupported.
+        exclude:
+          - os: macos-15-intel
+            python-version: '3.12'
         inputs: ["00_ or 01_ or 02_ or 03_ or 04_ or 05_ or 10_ or 20_ or 21_ or 22_ or 300_ or 30_ or 31_ or 32_ or 33_ or 34_ or 35_ or 36_", "51_ or 55_ or 56_ or 60_ or 61_ or 62_ or 63_ or 64_", "65_ or 66_ or 67_ or 68_ or 69_ or 70_ or 71_"]
     runs-on: ${{ matrix.os }}
     steps: