diff --git a/test/unit_test/runtime/fmt_test.cpp b/test/unit_test/runtime/fmt_test.cpp
index 600d491b..66031140 100644
--- a/test/unit_test/runtime/fmt_test.cpp
+++ b/test/unit_test/runtime/fmt_test.cpp
@@ -234,6 +234,18 @@ TEST_CASE("operator<< on a quantity", "[text][ostream][fmt]")
 
       SECTION("fmt with format {:%Q %q} on a quantity") { CHECK(MP_UNITS_STD_FMT::format("{:%Q %q}", q) == os.str()); }
     }
+
+    SECTION("radians")
+    {
+      const auto q = 42 * rad;
+      os << q;
+
+      SECTION("iostream") { CHECK(os.str() == "42 rad"); }
+
+      SECTION("fmt with default format {} on a quantity") { CHECK(MP_UNITS_STD_FMT::format("{}", q) == os.str()); }
+
+      SECTION("fmt with format {:%Q %q} on a quantity") { CHECK(MP_UNITS_STD_FMT::format("{:%Q %q}", q) == os.str()); }
+    }
   }
 
   SECTION("no space before unit symbol")
diff --git a/test/unit_test/static/unit_symbol_test.cpp b/test/unit_test/static/unit_symbol_test.cpp
index a642caaf..d2621d44 100644
--- a/test/unit_test/static/unit_symbol_test.cpp
+++ b/test/unit_test/static/unit_symbol_test.cpp
@@ -161,6 +161,9 @@ static_assert(unit_symbol(pow<1, 2>(metre)) == "m^(1/2)");
 static_assert(unit_symbol(pow<3, 5>(metre)) == "m^(3/5)");
 static_assert(unit_symbol(pow<1, 2>(metre / second)) == "m^(1/2)/s^(1/2)");
 
+// dimensionless unit
+static_assert(unit_symbol(radian) == "rad");
+
 // Physical constants
 static_assert(unit_symbol(si2019::speed_of_light_in_vacuum) == "c");
 static_assert(unit_symbol(gram * standard_gravity * si2019::speed_of_light_in_vacuum) == "c g g₀");