diff --git a/.github/workflows/CI.yaml b/.github/workflows/CI.yaml
index 2aaf0082..f6dad230 100644
--- a/.github/workflows/CI.yaml
+++ b/.github/workflows/CI.yaml
@@ -5,15 +5,24 @@ on:
     branches:
       - master
   pull_request:
+    branches:
+      - master
+  schedule:
+    - cron: "9 16 * * 1"
 
 jobs:
   test:
-    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
         python-version: ["3.7", "3.9", "3.11", "3.12"]
         pydantic-version: ["1", "2"]
+        runs-on: [ubuntu-latest, windows-latest]
+        exclude:
+          - runs-on: windows-latest
+            pydantic-version: "1"
+    name: "🐍 ${{ matrix.python-version }} • ${{ matrix.pydantic-version }} • ${{ matrix.runs-on }}"
+    runs-on: ${{ matrix.runs-on }}
 
     steps:
       - name: Set up Python ${{ matrix.python-version }}
@@ -30,9 +39,9 @@ jobs:
       # ^ start of line, pydantic, optional spaces and > sign, capture the version, replace with ^{version}
       # Should avoid also replacing the autodoc-pydantic spec later on.
       - name: Sed replace pydantic on repo
+        if: matrix.pydantic-version == '1'
         run: |
           sed -i 's/^pydantic *= *">*= *\([0-9.]*\)"/pydantic = "^\1"/' pyproject.toml
-        if: matrix.pydantic-version == '1'
       - name: Install repo with poetry (full deps)
         if: matrix.python-version != '3.9'
         run: poetry install --no-interaction --no-ansi --all-extras
@@ -62,7 +71,7 @@ jobs:
       - uses: actions/setup-python@v4
         name: Set up Python
         with:
-          python-version: "3.7"
+          python-version: "3.10"
       - name: Install poetry
         run: pip install poetry
       # Force pydantic 1.0 by modifying poetry dep "pydantic" string with in-place sed (see above for details)
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 789bb35b..b85044ab 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -20,7 +20,7 @@ Changelog
 .. +++++
 
 
-Unreleased
+0.27.0 / 2023-10-DD (Unreleased)
 -------------------
 
 Breaking Changes
@@ -40,11 +40,15 @@ Bug Fixes
 - (:pr:`325`, :issue:`324`) Ensure ``util.measure_coordinates`` isn't returning NaN angles just
    because floating-point errors are outside arccos's ``[-1, 1]`` bounds.
 - (:pr:`315`) Stop resetting numpy print formatting.
+- (:pr:`328`) Add workaround for only python v3.12.0 and psi4 (can be expanded) to handle
+  ``util.which`` on Windows when a cmd (non-executable) and a cmd.<executable_extension> live
+  side-by-side. Otherwise see ``[WinError 193] %1 is not a valid Win32 application``.
 
 Misc.
 +++++
 - (:pr:`320`) Reset ``black`` formatting to 2022.
 - (:pr:`327`) Enable Python v3.12 in poetry.
+- (:pr:`328`) Start Windows testing and cron testing.
 
 
 0.26.0 / 2023-07-31
diff --git a/qcelemental/tests/test_importing.py b/qcelemental/tests/test_importing.py
index 7bfcda97..2caed79c 100644
--- a/qcelemental/tests/test_importing.py
+++ b/qcelemental/tests/test_importing.py
@@ -117,7 +117,7 @@ def test_which_import_f_raisemsg_submodule():
 
 def test_which_t():
     ans = qcel.util.which("ls")
-    assert ans.split(os.path.sep)[-1] == "ls"
+    assert ans.split(os.path.sep)[-1] in ["ls", "ls.EXE"]
 
 
 def test_which_t_bool():
diff --git a/qcelemental/util/importing.py b/qcelemental/util/importing.py
index 8daaf264..009f6631 100644
--- a/qcelemental/util/importing.py
+++ b/qcelemental/util/importing.py
@@ -99,6 +99,11 @@ def which(
         lenv = {"PATH": os.pathsep.join([os.path.abspath(x) for x in env.split(os.pathsep) if x != ""])}
     lenv = {k: v for k, v in lenv.items() if v is not None}
 
+    if sys.platform == "win32" and sys.version_info >= (3, 12, 0) and sys.version_info < (3, 12, 1):
+        # https://github.com/python/cpython/issues/109590
+        if command == "psi4":
+            command = "psi4.bat"
+
     ans = shutil.which(command, mode=os.F_OK | os.X_OK, path=lenv["PATH"])
 
     # secondary check, see https://github.com/MolSSI/QCEngine/issues/292