diff --git a/au/code/au/apply_rational_magnitude_to_integral.hh b/au/code/au/apply_rational_magnitude_to_integral.hh
index 111d0beb..c7d7a738 100644
--- a/au/code/au/apply_rational_magnitude_to_integral.hh
+++ b/au/code/au/apply_rational_magnitude_to_integral.hh
@@ -75,9 +75,9 @@ constexpr T clamp_to_range_of(U x) {
 //
 
 template <typename... BPs>
-constexpr bool is_known_to_be_less_than_one(Magnitude<BPs...> m) {
+constexpr bool is_known_to_be_less_than_one(Magnitude<BPs...>) {
     using MagT = Magnitude<BPs...>;
-    static_assert(is_rational(m), "Magnitude must be rational");
+    static_assert(is_rational(MagT{}), "Magnitude must be rational");
 
     constexpr auto num_result = get_value_result<std::uintmax_t>(numerator(MagT{}));
     static_assert(num_result.outcome == MagRepresentationOutcome::OK,
diff --git a/au/code/au/math.hh b/au/code/au/math.hh
index b61b7aaf..90d61dfc 100644
--- a/au/code/au/math.hh
+++ b/au/code/au/math.hh
@@ -256,7 +256,7 @@ constexpr auto inverse_in(TargetUnits target_units, Quantity<U, R> q) {
     constexpr auto UNITY = make_constant(UnitProductT<>{});
 
     static_assert(
-        UNITY.in<R>(associated_unit(target_units) * U{}) >= threshold ||
+        UNITY.in<R>(associated_unit(TargetUnits{}) * U{}) >= threshold ||
             std::is_floating_point<R>::value,
         "Dangerous inversion risking truncation to 0; must supply explicit Rep if truly desired");
 
diff --git a/single-file-test.cc b/single-file-test.cc
index 439b7552..0ef9e02c 100644
--- a/single-file-test.cc
+++ b/single-file-test.cc
@@ -29,6 +29,8 @@ using namespace au;
 using ::au::symbols::m;
 using ::au::symbols::s;
 
+constexpr auto ns = ::au::nano(s);
+
 // 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) {
@@ -45,6 +47,10 @@ int main(int argc, char **argv) {
         {
             expect_equal((meters / second)(5) * seconds(6), meters(30)),
             expect_equal(SPEED_OF_LIGHT.as<int>(m / s), 299'792'458 * m / s),
+            expect_equal(detail::is_known_to_be_less_than_one(mag<5>() / mag<7>()), true),
+            expect_equal(detail::is_known_to_be_less_than_one(mag<7>() / mag<5>()), false),
+            expect_equal((10 * m).coerce_in(m * mag<5>() / mag<7>()), 14),
+            expect_equal(inverse_as(ns, 333 / s), 3'003'003 * ns),
         },
     };
     return std::all_of(std::begin(results), std::end(results), [](auto x) { return x; }) ? 0 : 1;