diff --git a/UnitTests/Tnef/TnefNameIdTests.cs b/UnitTests/Tnef/TnefNameIdTests.cs
index 9953cd733e..38ac53c3f4 100644
--- a/UnitTests/Tnef/TnefNameIdTests.cs
+++ b/UnitTests/Tnef/TnefNameIdTests.cs
@@ -69,6 +69,7 @@ public void TestEqualityById ()
 
 			Assert.That (tnef2.GetHashCode (), Is.EqualTo (tnef1.GetHashCode ()), "GetHashCode");
 			Assert.That (tnef2, Is.EqualTo (tnef1), "Equals");
+			Assert.That ((object) tnef2, Is.EqualTo ((object) tnef1), "Equals (object)");
 
 			Assert.That (tnef1 == tnef2, Is.True, "==");
 			Assert.That (tnef1 != tnef2, Is.False, "!=");
@@ -83,6 +84,7 @@ public void TestEqualityByName ()
 
 			Assert.That (tnef2.GetHashCode (), Is.EqualTo (tnef1.GetHashCode ()), "GetHashCode");
 			Assert.That (tnef2, Is.EqualTo (tnef1), "Equals");
+			Assert.That ((object) tnef2, Is.EqualTo ((object) tnef1), "Equals (object)");
 
 			Assert.That (tnef1 == tnef2, Is.True, "==");
 			Assert.That (tnef1 != tnef2, Is.False, "!=");
diff --git a/UnitTests/Tnef/TnefPropertyTagTests.cs b/UnitTests/Tnef/TnefPropertyTagTests.cs
index c3a32b6f94..b1091a45d0 100644
--- a/UnitTests/Tnef/TnefPropertyTagTests.cs
+++ b/UnitTests/Tnef/TnefPropertyTagTests.cs
@@ -51,6 +51,7 @@ public void TestBuiltIns ()
 
 				Assert.That (tag.GetHashCode (), Is.EqualTo (propertyTag.GetHashCode ()), $"{field.Name}.GetHashCode #1");
 				Assert.That (tag, Is.EqualTo (propertyTag), $"{field.Name}.Equals #1");
+				Assert.That ((object) tag, Is.EqualTo ((object) propertyTag), $"{field.Name}.Equals(object) #1");
 				Assert.That (tag == propertyTag, Is.True, $"{field.Name} == #1");
 				Assert.That (tag != propertyTag, Is.False, $"{field.Name} != #1");
 
@@ -64,6 +65,7 @@ public void TestBuiltIns ()
 
 				Assert.That (tag.GetHashCode (), Is.EqualTo (propertyTag.GetHashCode ()), $"{field.Name}.GetHashCode #2");
 				Assert.That (tag, Is.EqualTo (propertyTag), $"{field.Name}.Equals #2");
+				Assert.That ((object) tag, Is.EqualTo ((object) propertyTag), $"{field.Name}.Equals(object) #2");
 				Assert.That (tag == propertyTag, Is.True, $"{field.Name} == #2");
 				Assert.That (tag != propertyTag, Is.False, $"{field.Name} != #2");
 
@@ -77,6 +79,7 @@ public void TestBuiltIns ()
 
 				Assert.That (tag.GetHashCode (), Is.EqualTo (propertyTag.GetHashCode ()), $"{field.Name}.GetHashCode #3");
 				Assert.That (tag, Is.EqualTo (propertyTag), $"{field.Name}.Equals #3");
+				Assert.That ((object) tag, Is.EqualTo ((object) propertyTag), $"{field.Name}.Equals(object) #3");
 				Assert.That (tag == propertyTag, Is.True, $"{field.Name} == #3");
 				Assert.That (tag != propertyTag, Is.False, $"{field.Name} != #3");
 			}