diff --git a/src/Microsoft.Azure.EventHubs/Primitives/Guard.cs b/src/Microsoft.Azure.EventHubs/Primitives/Guard.cs
index 8446100..134d1c4 100644
--- a/src/Microsoft.Azure.EventHubs/Primitives/Guard.cs
+++ b/src/Microsoft.Azure.EventHubs/Primitives/Guard.cs
@@ -9,7 +9,7 @@ internal static void ArgumentNotNull(string argumentName, object value)
         {
             if (value == null)
             {
-                Fx.Exception.ArgumentNull(argumentName);
+                throw Fx.Exception.ArgumentNull(argumentName);
             }
         }
 
@@ -17,7 +17,7 @@ internal static void ArgumentNotNullOrWhiteSpace(string argumentName, string val
         {
             if (string.IsNullOrWhiteSpace(value))
             {
-                Fx.Exception.ArgumentNull(argumentName);
+                throw Fx.Exception.ArgumentNull(argumentName);
             }
         }
     }
diff --git a/test/Microsoft.Azure.EventHubs.Tests/Client/NegativeCases.cs b/test/Microsoft.Azure.EventHubs.Tests/Client/NegativeCases.cs
index 7ad432b..17be408 100644
--- a/test/Microsoft.Azure.EventHubs.Tests/Client/NegativeCases.cs
+++ b/test/Microsoft.Azure.EventHubs.Tests/Client/NegativeCases.cs
@@ -130,7 +130,7 @@ await Assert.ThrowsAsync<ArgumentOutOfRangeException>(async () =>
             invalidPartitions = new List<string>() { "", " ", null };
             foreach (var invalidPartitionId in invalidPartitions)
             {
-                await Assert.ThrowsAsync<ArgumentException>(async () =>
+                await Assert.ThrowsAsync<ArgumentNullException>(async () =>
                 {
                     TestUtility.Log($"Sending to invalid partition {invalidPartitionId}");
                     sender = this.EventHubClient.CreatePartitionSender(invalidPartitionId);
@@ -162,7 +162,7 @@ await Assert.ThrowsAsync<InvalidOperationException>(async () =>
             invalidPartitions = new List<string>() { "", " ", null };
             foreach (var invalidPartitionId in invalidPartitions)
             {
-                await Assert.ThrowsAsync<ArgumentException>(async () =>
+                await Assert.ThrowsAsync<ArgumentNullException>(async () =>
                 {
                     TestUtility.Log($"Getting partition information from invalid partition {invalidPartitionId}");
                     await this.EventHubClient.GetPartitionRuntimeInformationAsync(invalidPartitionId);
@@ -179,7 +179,7 @@ Task CreateClientWithoutEntityPathShouldFail()
             var csb = new EventHubsConnectionStringBuilder(TestUtility.EventHubsConnectionString);
             csb.EntityPath = null;
 
-            return Assert.ThrowsAsync<ArgumentException>(() =>
+            return Assert.ThrowsAsync<ArgumentNullException>(() =>
             {
                 EventHubClient.CreateFromConnectionString(csb.ToString());
                 throw new Exception("Entity path wasn't provided in the connection string and this new call was supposed to fail");