diff --git a/BlendFile/Reader.cs b/BlendFile/Reader.cs
index a227578..677e2eb 100644
--- a/BlendFile/Reader.cs
+++ b/BlendFile/Reader.cs
@@ -120,8 +120,8 @@ public class Reader {
     /// <returns></returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private long GetFieldDataOffset(int fieldIndex, FieldInfo[] fieldMetadata) =>
-        fieldMetadata.Where(f => f.GetCustomAttribute<DNAFieldAttribute>()!.OriginalIndex < fieldIndex)
-        .Sum(f => f.GetCustomAttribute<DNAFieldAttribute>()!.Size);
+        fieldMetadata.First(x => x.GetCustomAttribute<DNAFieldAttribute>()!.OriginalIndex == fieldIndex)
+            .GetCustomAttribute<DNAFieldAttribute>()!.MemoryOffset;
     
     /// <summary>
     /// Creates an instance of a given type
@@ -147,7 +147,7 @@ public class Reader {
             
             //Calculate the offset from where the data of the field starts.
             //Because the order of the fields is not guaranteed we need to compute it each time
-            long offset = GetFieldDataOffset(attrib.OriginalIndex, fieldMetadata);
+            long offset = attrib.MemoryOffset;
             
             int size = attrib.Size;
             var data = new byte[size];