diff --git a/test/Polar_test.cc b/test/Polar_test.cc
index bd1a3b4..7ef43ca 100644
--- a/test/Polar_test.cc
+++ b/test/Polar_test.cc
@@ -68,7 +68,7 @@ TEST(Polar, FromSpherical) {
   EXPECT_FLOAT_EQ(p.angle, 0.0F) << "p.angle FromSpherical(0 0 90)";
 }
 
-TEST(Polar, Negate) {
+TEST(Polar, Negation) {
   Polar v = Polar(2, 45);
   Polar r = Polar::zero;
 
@@ -92,4 +92,17 @@ TEST(Polar, Negate) {
   EXPECT_TRUE(r == Polar(0, 0)) << "Negate(0 0)";
 }
 
+TEST(Polar, Subtraction) {
+  Polar v1 = Polar(4, 45);
+  Polar v2 = Polar(1, -90);
+  Polar r = Polar::zero;
+
+  r = v1 - v2;
+  // don't know what to expect yet
+
+  v2 = Polar::zero;
+  r = v1 - v2;
+  EXPECT_FLOAT_EQ(r.distance, v1.distance) << "Subtraction(0 0)";
+}
+
 #endif
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