diff --git a/src/Umbraco.Core/PropertyEditors/ValueConverters/MultipleTextStringValueConverter.cs b/src/Umbraco.Core/PropertyEditors/ValueConverters/MultipleTextStringValueConverter.cs
index 39bcf85b12..a3b12a6688 100644
--- a/src/Umbraco.Core/PropertyEditors/ValueConverters/MultipleTextStringValueConverter.cs
+++ b/src/Umbraco.Core/PropertyEditors/ValueConverters/MultipleTextStringValueConverter.cs
@@ -28,7 +28,7 @@ namespace Umbraco.Core.PropertyEditors.ValueConverters
             //    </values>
             // </keyFeatureList>
 
-            var sourceString = source.ToString();
+            var sourceString = source != null ? source.ToString() : null;
             if (string.IsNullOrWhiteSpace(sourceString)) return Enumerable.Empty<string>();
 
             //SD: I have no idea why this logic is here, I'm pretty sure we've never saved the multiple txt string