diff --git a/SabreTools.Library/DatFiles/Listxml.cs b/SabreTools.Library/DatFiles/Listxml.cs
index c09d7e69..4fe5bd7d 100644
--- a/SabreTools.Library/DatFiles/Listxml.cs
+++ b/SabreTools.Library/DatFiles/Listxml.cs
@@ -771,7 +771,7 @@ namespace SabreTools.Library.DatFiles
                     case "diplocation":
                         var dipLocation = new Location();
                         dipLocation.Name = reader.GetAttribute("name");
-                        dipLocation.Number = reader.GetAttribute("number");
+                        dipLocation.Number = Sanitizer.CleanLong(reader.GetAttribute("number"));
                         dipLocation.Inverted = reader.GetAttribute("inverted").AsYesNo();
 
                         dipSwitch.Locations.Add(dipLocation);
@@ -895,7 +895,7 @@ namespace SabreTools.Library.DatFiles
                     case "conflocation":
                         var confLocation = new Location();
                         confLocation.Name = reader.GetAttribute("name");
-                        confLocation.Number = reader.GetAttribute("number");
+                        confLocation.Number = Sanitizer.CleanLong(reader.GetAttribute("number"));
                         confLocation.Inverted = reader.GetAttribute("inverted").AsYesNo();
 
                         configuration.Locations.Add(confLocation);
@@ -1396,7 +1396,7 @@ namespace SabreTools.Library.DatFiles
                             {
                                 xtw.WriteStartElement("conflocation");
                                 xtw.WriteOptionalAttributeString("name", location.Name);
-                                xtw.WriteOptionalAttributeString("number", location.Number);
+                                xtw.WriteOptionalAttributeString("number", location.Number?.ToString());
                                 xtw.WriteOptionalAttributeString("inverted", location.Inverted.FromYesNo());
                                 xtw.WriteEndElement();
                             }
@@ -1476,7 +1476,7 @@ namespace SabreTools.Library.DatFiles
                             {
                                 xtw.WriteStartElement("diplocation");
                                 xtw.WriteOptionalAttributeString("name", location.Name);
-                                xtw.WriteOptionalAttributeString("number", location.Number);
+                                xtw.WriteOptionalAttributeString("number", location.Number?.ToString());
                                 xtw.WriteOptionalAttributeString("inverted", location.Inverted.FromYesNo());
                                 xtw.WriteEndElement();
                             }
diff --git a/SabreTools.Library/DatFiles/SabreDat.cs b/SabreTools.Library/DatFiles/SabreDat.cs
index edb8809b..d8cb1276 100644
--- a/SabreTools.Library/DatFiles/SabreDat.cs
+++ b/SabreTools.Library/DatFiles/SabreDat.cs
@@ -732,7 +732,7 @@ namespace SabreTools.Library.DatFiles
                     case "conflocation":
                         var confLocation = new Location();
                         confLocation.Name = reader.GetAttribute("name");
-                        confLocation.Number = reader.GetAttribute("number");
+                        confLocation.Number = Sanitizer.CleanLong(reader.GetAttribute("number"));
                         confLocation.Inverted = reader.GetAttribute("inverted").AsYesNo();
 
                         (configuration as Configuration).Locations.Add(confLocation);
@@ -860,7 +860,7 @@ namespace SabreTools.Library.DatFiles
                     case "diplocation":
                         var dipLocation = new Location();
                         dipLocation.Name = reader.GetAttribute("name");
-                        dipLocation.Number = reader.GetAttribute("number");
+                        dipLocation.Number = Sanitizer.CleanLong(reader.GetAttribute("number"));
                         dipLocation.Inverted = reader.GetAttribute("inverted").AsYesNo();
 
                         (dipSwitch as DipSwitch).Locations.Add(dipLocation);
@@ -1298,7 +1298,7 @@ namespace SabreTools.Library.DatFiles
                             {
                                 xtw.WriteStartElement("conflocation");
                                 xtw.WriteOptionalAttributeString("name", location.Name);
-                                xtw.WriteOptionalAttributeString("number", location.Number);
+                                xtw.WriteOptionalAttributeString("number", location.Number?.ToString());
                                 xtw.WriteOptionalAttributeString("inverted", location.Inverted.FromYesNo());
                                 xtw.WriteEndElement();
                             }
@@ -1381,7 +1381,7 @@ namespace SabreTools.Library.DatFiles
                             {
                                 xtw.WriteStartElement("diplocation");
                                 xtw.WriteOptionalAttributeString("name", location.Name);
-                                xtw.WriteOptionalAttributeString("number", location.Number);
+                                xtw.WriteOptionalAttributeString("number", location.Number?.ToString());
                                 xtw.WriteOptionalAttributeString("inverted", location.Inverted.FromYesNo());
                                 xtw.WriteEndElement();
                             }
diff --git a/SabreTools.Library/DatItems/Location.cs b/SabreTools.Library/DatItems/Location.cs
index 69f467e1..246a540e 100644
--- a/SabreTools.Library/DatItems/Location.cs
+++ b/SabreTools.Library/DatItems/Location.cs
@@ -26,7 +26,7 @@ namespace SabreTools.Library.DatItems
         /// Location ID
         /// </summary>
         [JsonProperty("number", DefaultValueHandling = DefaultValueHandling.Ignore)]
-        public string Number { get; set; }
+        public long? Number { get; set; }
 
         /// <summary>
         /// Determines if location is inverted or not
@@ -61,7 +61,7 @@ namespace SabreTools.Library.DatItems
                 Name = mappings[Field.DatItem_Location_Name];
 
             if (mappings.Keys.Contains(Field.DatItem_Location_Number))
-                Number = mappings[Field.DatItem_Location_Number];
+                Number = Sanitizer.CleanLong(mappings[Field.DatItem_Location_Number]);
 
             if (mappings.Keys.Contains(Field.DatItem_Location_Inverted))
                 Inverted = mappings[Field.DatItem_Location_Inverted].AsYesNo();
@@ -169,9 +169,11 @@ namespace SabreTools.Library.DatItems
                 return false;
 
             // Filter on number
-            if (filter.DatItem_Location_Number.MatchesPositiveSet(Number) == false)
+            if (filter.DatItem_Location_Number.MatchesNeutral(null, Number) == false)
                 return false;
-            if (filter.DatItem_Location_Number.MatchesNegativeSet(Number) == true)
+            else if (filter.DatItem_Location_Number.MatchesPositive(null, Number) == false)
+                return false;
+            else if (filter.DatItem_Location_Number.MatchesNegative(null, Number) == false)
                 return false;
 
             // Filter on inverted
diff --git a/SabreTools.Library/Filtering/Filter.cs b/SabreTools.Library/Filtering/Filter.cs
index 4a742dcf..b9482547 100644
--- a/SabreTools.Library/Filtering/Filter.cs
+++ b/SabreTools.Library/Filtering/Filter.cs
@@ -235,7 +235,7 @@ namespace SabreTools.Library.Filtering
 
         // Location
         public FilterItem<string> DatItem_Location_Name { get; private set; } = new FilterItem<string>();
-        public FilterItem<string> DatItem_Location_Number { get; private set; } = new FilterItem<string>();
+        public FilterItem<long?> DatItem_Location_Number { get; private set; } = new FilterItem<long?>() { Positive = null, Negative = null, Neutral = null };
         public FilterItem<bool?> DatItem_Location_Inverted { get; private set; } = new FilterItem<bool?>() { Neutral = null };
         
         // Part
@@ -974,7 +974,7 @@ namespace SabreTools.Library.Filtering
                     break;
 
                 case Field.DatItem_Location_Number:
-                    SetStringFilter(DatItem_Location_Number, value, negate);
+                    SetLongFilter(DatItem_Location_Number, value, negate);
                     break;
 
                 case Field.DatItem_Location_Inverted: