diff --git a/src/coreclr/tools/Common/TypeSystem/Common/ExplicitLayoutValidator.cs b/src/coreclr/tools/Common/TypeSystem/Common/ExplicitLayoutValidator.cs
index 07489f82c976aa..715afb935de0ff 100644
--- a/src/coreclr/tools/Common/TypeSystem/Common/ExplicitLayoutValidator.cs
+++ b/src/coreclr/tools/Common/TypeSystem/Common/ExplicitLayoutValidator.cs
@@ -53,7 +53,7 @@ public int CompareTo(FieldLayoutInterval other)
 
         // Represent field layout bits as as a series of intervals to prevent pathological bad behavior
         // involving excessively large explicit layout structures.
-        private readonly List<FieldLayoutInterval> _fieldLayout = new List<FieldLayoutInterval>();
+        private readonly List<FieldLayoutInterval> _fieldLayout;
 
         private readonly MetadataType _typeBeingValidated;
 
@@ -61,6 +61,7 @@ private ExplicitLayoutValidator(MetadataType type, int typeSizeInBytes)
         {
             _typeBeingValidated = type;
             _pointerSize = type.Context.Target.PointerSize;
+            _fieldLayout = new List<FieldLayoutInterval>();
         }
 
         public static void Validate(MetadataType type, ComputedInstanceFieldLayout layout)