diff --git a/.github/workflows/single-file-build-and-test.yml b/.github/workflows/single-file-build-and-test.yml
new file mode 100644
index 00000000..262e8b79
--- /dev/null
+++ b/.github/workflows/single-file-build-and-test.yml
@@ -0,0 +1,50 @@
+# Copyright 2023 Aurora Operations, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: single-file-build-and-test
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    strategy:
+      matrix:
+        windows: [windows-2019, windows-2022]
+
+    runs-on: ${{ matrix.windows }}
+
+    steps:
+      - uses: actions/checkout@dc323e67f16fb5f7663d20ff7941f27f5809e9b6 #v2.6.0
+
+      - name: Set up developer command prompt
+        uses: ilammy/msvc-dev-cmd@cec98b9d092141f74527d0afa6feb2af698cfe89 #v1.12.1
+
+      - name: Set up python
+        uses: actions/setup-python@3542bca2639a428e1796aaa6a2ffef0c0f575566 #v3.1.4
+        with:
+          python-version: '3.10'
+
+      - name: Build single-file package
+        shell: cmd
+        run: python tools/bin/make-single-file --units meters seconds --version-id NA > au.hh
+
+      - name: Build and run test
+        shell: cmd
+        run: |
+          cl.exe /std:c++14 single-file-test.cc
+          single-file-test.exe
diff --git a/au/quantity.hh b/au/quantity.hh
index fa30a76e..1f706a98 100644
--- a/au/quantity.hh
+++ b/au/quantity.hh
@@ -142,8 +142,8 @@ class Quantity {
     template <typename NewRep,
               typename NewUnit,
               typename = std::enable_if_t<IsUnit<NewUnit>::value>>
-    constexpr auto as(NewUnit u) const {
-        constexpr auto ratio = unit_ratio(unit, u);
+    constexpr auto as(NewUnit) const {
+        constexpr auto ratio = unit_ratio(unit, NewUnit{});
 
         using Common = std::common_type_t<Rep, NewRep>;
         constexpr auto NUM = integer_part(numerator(ratio));
@@ -158,7 +158,7 @@ class Quantity {
 
     template <typename NewUnit, typename = std::enable_if_t<IsUnit<NewUnit>::value>>
     constexpr auto as(NewUnit u) const {
-        static_assert(implicit_rep_permitted_from_source_to_target<Rep>(unit, u),
+        static_assert(implicit_rep_permitted_from_source_to_target<Rep>(unit, NewUnit{}),
                       "Dangerous conversion: use .as<Rep>(NewUnit) instead");
         return as<Rep>(u);
     }
diff --git a/single-file-test.cc b/single-file-test.cc
new file mode 100644
index 00000000..62e8bd99
--- /dev/null
+++ b/single-file-test.cc
@@ -0,0 +1,48 @@
+// Copyright 2023 Aurora Operations, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <algorithm>
+#include <iostream>
+#include <vector>
+
+#include "au.hh"
+
+// This file builds all of the code in the single-file package of Au, and runs some basic tests.
+//
+// If we find any failures not covered by this file, we can add more test cases as needed.
+//
+// Note that this file will *not* be built with bazel.  It's therefore important that we avoid all
+// dependencies outside of the C++14 standard library, and the single-file package of Au itself.
+
+using namespace au;
+
+// This ad hoc utility is a stand-in for GTEST, which we can't use here.
+template <typename ExpectedT, typename ActualT>
+bool expect_equal(ExpectedT expected, ActualT actual) {
+    if (expected != actual) {
+        std::cerr << "Failure!  Expected (" << expected << "); Actual (" << actual << ")"
+                  << std::endl;
+        return false;
+    }
+    return true;
+}
+
+int main(int argc, char **argv) {
+    const std::vector<bool> results{
+        {
+            expect_equal((meters / second)(5) * seconds(6), meters(30)),
+        },
+    };
+    return std::all_of(std::begin(results), std::end(results), [](auto x) { return x; }) ? 0 : 1;
+}