diff --git a/src/Umbraco.Core/Models/ContentTypeBase.cs b/src/Umbraco.Core/Models/ContentTypeBase.cs
index c1c8e3270c..2398a6c2e6 100644
--- a/src/Umbraco.Core/Models/ContentTypeBase.cs
+++ b/src/Umbraco.Core/Models/ContentTypeBase.cs
@@ -533,6 +533,18 @@ namespace Umbraco.Core.Models
         /// <param name="propertyGroupName">Name of the <see cref="PropertyGroup"/> to remove</param>
         public void RemovePropertyGroup(string propertyGroupName)
         {
+            // if no group exists with that name, do nothing
+            var group = PropertyGroups[propertyGroupName];
+            if (group == null) return;
+
+            // re-assign the group's properties to no group
+            foreach (var property in group.PropertyTypes)
+            {
+                property.PropertyGroupId = new Lazy<int>(() => 0);
+                _propertyTypes.Add(property);
+            }
+
+            // actually remove the group
             PropertyGroups.RemoveItem(propertyGroupName);
             OnPropertyChanged(PropertyGroupCollectionSelector);
         }
diff --git a/src/Umbraco.Web/umbraco.presentation/umbraco/controls/ContentTypeControlNew.ascx.cs b/src/Umbraco.Web/umbraco.presentation/umbraco/controls/ContentTypeControlNew.ascx.cs
index eed2947b23..44b4da1864 100644
--- a/src/Umbraco.Web/umbraco.presentation/umbraco/controls/ContentTypeControlNew.ascx.cs
+++ b/src/Umbraco.Web/umbraco.presentation/umbraco/controls/ContentTypeControlNew.ascx.cs
@@ -1475,7 +1475,8 @@ jQuery(document).ready(function() {{ refreshDropDowns(); }});
                     var propertyGroup = _contentType.ContentTypeItem.PropertyGroups.FirstOrDefault(x => x.Id == propertyGroupId);
                     if (propertyGroup != null && string.IsNullOrEmpty(propertyGroup.Name) == false)
                     {
-                        _contentType.ContentTypeItem.PropertyGroups.Remove(propertyGroup.Name);
+                        // use RemovePropertyGroup so properties become generic
+                        _contentType.ContentTypeItem.RemovePropertyGroup(propertyGroup.Name);
                         _contentType.Save();
                     }
                 //}