diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e59c2b54..7a7c61ac0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -48,7 +48,7 @@ different versioning scheme, following the Haskell community's
 
 ### C# ###
 
-* There were no C# changes in this release.
+* Fixed compatibility with .NET 9.
 
 ## 13.0 ##
 
diff --git a/cs/src/core/expressions/DeserializerTransform.cs b/cs/src/core/expressions/DeserializerTransform.cs
index b89e1dfbb..8d7feab03 100644
--- a/cs/src/core/expressions/DeserializerTransform.cs
+++ b/cs/src/core/expressions/DeserializerTransform.cs
@@ -523,7 +523,7 @@ Expression Container(IParser parser, Expression container, Type schemaType, bool
                         else
                         {
                             var capacity = container.Type.GetDeclaredProperty("Capacity", count.Type);
-                            if (capacity != null)
+                            if (capacity != null && capacity.CanWrite)
                             {
                                 var cappedCount = Expression.Variable(typeof(int), container + "_count");
                                 beforeLoop = ApplyCountCap(