diff --git a/src/Hl7.Fhir.Base/ElementModel/ReferencedResourceCache.cs b/src/Hl7.Fhir.Base/ElementModel/ReferencedResourceCache.cs
index ea215d5071..80c53ca7ac 100644
--- a/src/Hl7.Fhir.Base/ElementModel/ReferencedResourceCache.cs
+++ b/src/Hl7.Fhir.Base/ElementModel/ReferencedResourceCache.cs
@@ -8,25 +8,37 @@ namespace Hl7.Fhir.ElementModel;
 
 internal class ReferencedResourceCache : IEnumerable<ScopedNode.BundledResource>
 {
-    private Dictionary<string, ScopedNode?> _items;
+    private Dictionary<string, ScopedNode> _items;
+    private List<ScopedNode> _unreferenceableItems; // some resources may not have a reference, but are included nonetheless.
     
-    public ReferencedResourceCache(IEnumerable<KeyValuePair<string, ScopedNode?>> items)
+    public ReferencedResourceCache(IEnumerable<KeyValuePair<string, ScopedNode>> items)
     {
-        _items = new Dictionary<string, ScopedNode?>();
+        _items = new Dictionary<string, ScopedNode>();
+        _unreferenceableItems = [];
         foreach (var item in items)
         {
-            _items.Add(item.Key, item.Value);
+            if (item.Key is not null)
+                _items.Add(item.Key, item.Value);
+            else 
+                _unreferenceableItems.Add(item.Value);
+                
         }
     }
     
-    internal IEnumerable<ScopedNode> Resources => _items.Values.OfType<ScopedNode>();
+    internal IEnumerable<ScopedNode> Resources => _items.Values.Concat(_unreferenceableItems);
 
     internal ScopedNode? ResolveReference(string reference)
     {
         return _items.TryGetValue(reference, out var node) ? node : null;
     }
 
-    public IEnumerator<ScopedNode.BundledResource> GetEnumerator() => _items.Select(i => new ScopedNode.BundledResource(i.Key, i.Value)).GetEnumerator();
+    public IEnumerator<ScopedNode.BundledResource> GetEnumerator() => 
+        _items
+            .Select(i => new ScopedNode.BundledResource(i.Key, i.Value))
+            .Concat(
+                _unreferenceableItems.Select(i => new ScopedNode.BundledResource(null, i))
+            )
+            .GetEnumerator();
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 }
 
diff --git a/src/Hl7.Fhir.ElementModel.Shared.Tests/ScopedNodeTests.cs b/src/Hl7.Fhir.ElementModel.Shared.Tests/ScopedNodeTests.cs
index d42860a80a..407a83bdd0 100644
--- a/src/Hl7.Fhir.ElementModel.Shared.Tests/ScopedNodeTests.cs
+++ b/src/Hl7.Fhir.ElementModel.Shared.Tests/ScopedNodeTests.cs
@@ -1,4 +1,5 @@
-using Hl7.Fhir.Model;
+using FluentAssertions;
+using Hl7.Fhir.Model;
 using Hl7.Fhir.Serialization;
 using Hl7.Fhir.Specification;
 using Hl7.Fhir.Specification.Snapshot;
@@ -273,6 +274,15 @@ static bool CCDATypeNameMapper(string typeName, out string canonical)
 
 
         }
+        
+        [TestMethod]
+        public void Bundle_WithEntryWithoutFullUrl_ShouldNotThrow()
+        {
+            var bundle = new Bundle() { Type = Bundle.BundleType.Batch, Entry = [new Bundle.EntryComponent() { Resource = new Patient() }]}.ToTypedElement().ToScopedNode();
+
+            var enumerate = () => bundle.BundledResources();
+            enumerate.Should().NotThrow().Subject.Should().ContainSingle(c => c.FullUrl == null);
+        }
 
         private class CCDAResourceResolver : IAsyncResourceResolver
         {