diff --git a/IFCGeoRefCheckerCommand/IFCGeoRefCheckerCommand.csproj b/IFCGeoRefCheckerCommand/IFCGeoRefCheckerCommand.csproj
index bdf92bc..2d82077 100644
--- a/IFCGeoRefCheckerCommand/IFCGeoRefCheckerCommand.csproj
+++ b/IFCGeoRefCheckerCommand/IFCGeoRefCheckerCommand.csproj
@@ -25,8 +25,9 @@
     <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
     <PackageReference Include="Serilog.Sinks.Console" Version="4.1.0" />
     <PackageReference Include="Serilog.Sinks.File" Version="5.0.0" />
-    <PackageReference Include="Xbim.Common" Version="5.1.341" />
-    <PackageReference Include="Xbim.Ifc" Version="5.1.341" />
+    <PackageReference Include="Xbim.Common" Version="6.0.445" />
+    <PackageReference Include="Xbim.Essentials" Version="6.0.445" />
+    <PackageReference Include="Xbim.Ifc" Version="6.0.445" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/IFCGeoRefCheckerGUI/IFCGeoRefCheckerGUI.csproj b/IFCGeoRefCheckerGUI/IFCGeoRefCheckerGUI.csproj
index 6c8309a..2ea4fef 100644
--- a/IFCGeoRefCheckerGUI/IFCGeoRefCheckerGUI.csproj
+++ b/IFCGeoRefCheckerGUI/IFCGeoRefCheckerGUI.csproj
@@ -27,9 +27,9 @@
     <PackageReference Include="GDAL" Version="3.6.3" />
     <PackageReference Include="GDAL.Native" Version="3.6.3" />
     <PackageReference Include="Serilog.Sinks.RichTextBox.Wpf" Version="1.1.0" />
-    <PackageReference Include="Xbim.Common" Version="5.1.341" />
-    <PackageReference Include="Xbim.Essentials" Version="5.1.341" />
-    <PackageReference Include="Xbim.Ifc" Version="5.1.341" />
+    <PackageReference Include="Xbim.Common" Version="6.0.445" />
+    <PackageReference Include="Xbim.Essentials" Version="6.0.445" />
+    <PackageReference Include="Xbim.Ifc" Version="6.0.445" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/IFCGeorefShared/GeoRefChecker.cs b/IFCGeorefShared/GeoRefChecker.cs
index 6d0bc1e..7437df8 100644
--- a/IFCGeorefShared/GeoRefChecker.cs
+++ b/IFCGeorefShared/GeoRefChecker.cs
@@ -826,7 +826,11 @@ private string WriteResultLvl50()
                     sb.AppendLine($"{_translationService.Translate("TargetCRS", CultureInfo.CurrentCulture)} {lvl50.MapConversion.TargetCRS.Name}");
                     sb.AppendLine($"{_translationService.Translate("Description", CultureInfo.CurrentCulture)} {(lvl50.MapConversion.TargetCRS.Description.HasValue ? lvl50.MapConversion.TargetCRS.Description : "not specified")}");
                     sb.AppendLine($"{_translationService.Translate("GeoDatum", CultureInfo.CurrentCulture)} {(lvl50.MapConversion.TargetCRS.GeodeticDatum.HasValue ? lvl50.MapConversion.TargetCRS.GeodeticDatum : "not specified")}");
-                    sb.AppendLine($"{_translationService.Translate("VertDatum", CultureInfo.CurrentCulture)} {(lvl50.MapConversion.TargetCRS.VerticalDatum.HasValue ? lvl50.MapConversion.TargetCRS.VerticalDatum : "not specified")}");
+
+                    if (lvl50.ProjectedCRS4x3 != null)
+                    {
+                        sb.AppendLine($"{_translationService.Translate("VertDatum", CultureInfo.CurrentCulture)} {(lvl50.ProjectedCRS4x3.VerticalDatum.HasValue ? lvl50.ProjectedCRS4x3.VerticalDatum : "not specified")}");
+                    }
 
                     sb.AppendLine();
                     sb.AppendLine($"LoGeoRef50 {_translationService.Translate("Fulfilled", CultureInfo.CurrentCulture)}");
diff --git a/IFCGeorefShared/Levels/Level50.cs b/IFCGeorefShared/Levels/Level50.cs
index 117a689..6ece74c 100644
--- a/IFCGeorefShared/Levels/Level50.cs
+++ b/IFCGeorefShared/Levels/Level50.cs
@@ -2,11 +2,13 @@
 using System.Collections.Generic;
 using System.Text;
 using Xbim.Ifc4.Interfaces;
+using Xbim.Ifc4x3.RepresentationResource;
 
 namespace IFCGeorefShared.Levels
 {
     public class Level50 : Level40
     {
         public IIfcMapConversion? MapConversion;
+        public IfcProjectedCRS? ProjectedCRS4x3;
     }
 }