diff --git a/src/WorkItemMigrator/WorkItemImport/WitClient/WitClientUtils.cs b/src/WorkItemMigrator/WorkItemImport/WitClient/WitClientUtils.cs
index ace9317a..f467c6c5 100644
--- a/src/WorkItemMigrator/WorkItemImport/WitClient/WitClientUtils.cs
+++ b/src/WorkItemMigrator/WorkItemImport/WitClient/WitClientUtils.cs
@@ -668,11 +668,12 @@ private void CorrectClosedByAndClosedDate(WiRevision rev, WorkItem wi)
                         wiState.Equals("Done", StringComparison.InvariantCultureIgnoreCase)
                         || wiState.Equals("Closed", StringComparison.InvariantCultureIgnoreCase)
                     )
-                    && revState.Equals("New", StringComparison.InvariantCultureIgnoreCase)
+                    && !(revState.Equals("Done", StringComparison.InvariantCultureIgnoreCase)
+                    || revState.Equals("Closed", StringComparison.InvariantCultureIgnoreCase))
                 )
             {
-                rev.Fields.Add(new WiField() { ReferenceName = WiFieldReference.ClosedDate, Value = null });
-                rev.Fields.Add(new WiField() { ReferenceName = WiFieldReference.ClosedBy, Value = null });
+                rev.Fields.Add(new WiField() { ReferenceName = WiFieldReference.ClosedDate, Value = "" });
+                rev.Fields.Add(new WiField() { ReferenceName = WiFieldReference.ClosedBy, Value = "" });
             }
 
             if (
diff --git a/src/WorkItemMigrator/tests/Migration.Wi-Import.Tests/WitClient/WitClientUtilsTests.cs b/src/WorkItemMigrator/tests/Migration.Wi-Import.Tests/WitClient/WitClientUtilsTests.cs
index 81e9fded..d316f5ff 100644
--- a/src/WorkItemMigrator/tests/Migration.Wi-Import.Tests/WitClient/WitClientUtilsTests.cs
+++ b/src/WorkItemMigrator/tests/Migration.Wi-Import.Tests/WitClient/WitClientUtilsTests.cs
@@ -335,8 +335,8 @@ public void When_calling_ensure_fields_on_state_change_with_subsequent_revision_
             Assert.Multiple(() =>
             {
                 Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.State), Is.EqualTo("New"));
-                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedDate), Is.EqualTo(null));
-                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedBy), Is.EqualTo(null));
+                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedDate), Is.EqualTo(""));
+                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedBy), Is.EqualTo(""));
                 Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ActivatedDate), Is.EqualTo(null));
                 Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ActivatedBy), Is.EqualTo(null));
             });
@@ -365,8 +365,8 @@ public void When_calling_ensure_fields_on_a_closed_user_Story_with_Then_closed_d
             Assert.Multiple(() =>
             {
                 Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.State), Is.EqualTo("New"));
-                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedDate), Is.EqualTo(null));
-                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedBy), Is.EqualTo(null));
+                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedDate), Is.EqualTo(""));
+                Assert.That(rev.Fields.GetFieldValueOrDefault<string>(WiFieldReference.ClosedBy), Is.EqualTo(""));
             });
         }