diff --git a/BritishHorseRacingApi.Tests/DataConverterHelperTests.cs b/BritishHorseRacingApi.Tests/DataConverterHelperTests.cs
index 71726a1..1cb6103 100644
--- a/BritishHorseRacingApi.Tests/DataConverterHelperTests.cs
+++ b/BritishHorseRacingApi.Tests/DataConverterHelperTests.cs
@@ -39,14 +39,16 @@ namespace BritishHorseRacingApi.Tests
         [InlineData("1m 1f 104y", 2084)]
         [InlineData("1f 104y", 324)]
         [InlineData("104y", 104)]
-        public void TestDistanceStringToYardsConversion(string distance, int expectedResult)
+        [InlineData("", null)]
+        [InlineData(" ", null)]
+        [InlineData(null, null)]
+        public void TestDistanceStringToYardsConversion(string distance, int? expectedResult)
         {
             //Arrange
             //Act
             var result = DataConverterHelper.DistanceStringToYards(distance);
             //Assert
-            Assert.True(result.HasValue);
-            Assert.Equal(expectedResult, result.Value);
+            Assert.Equal(expectedResult, result);
         }
     }
 }