diff --git a/WAD/Header.cs b/WAD/Header.cs
index f544587..e49a7e8 100644
--- a/WAD/Header.cs
+++ b/WAD/Header.cs
@@ -1,12 +1,26 @@
+using System.Runtime.InteropServices;
+
 namespace SabreTools.Models.WAD
 {
     /// <see href="https://github.com/RavuAlHemio/hllib/blob/master/HLLib/WADFile.h"/>
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
     public sealed class Header
     {
-        public string? Signature { get; set; }
-        
-        public uint LumpCount { get; set; }
-        
-        public uint LumpOffset { get; set; }
+        /// <summary>
+        /// "WAD3"
+        /// </summary>
+        /// <remarks>4 bytes</remarks>
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 4)]
+        public string? Signature;
+
+        /// <summary>
+        /// Number of lumps in the file
+        /// </summary>
+        public uint LumpCount;
+
+        /// <summary>
+        /// Offset where lumps are stored
+        /// </summary>
+        public uint LumpOffset;
     }
 }
diff --git a/WAD/Lump.cs b/WAD/Lump.cs
index a184507..5ba8aa5 100644
--- a/WAD/Lump.cs
+++ b/WAD/Lump.cs
@@ -1,22 +1,27 @@
+using System.Runtime.InteropServices;
+
 namespace SabreTools.Models.WAD
 {
     /// <see href="https://github.com/RavuAlHemio/hllib/blob/master/HLLib/WADFile.h"/>
+    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
     public sealed class Lump
     {
-        public uint Offset { get; set; }
+        public uint Offset;
 
-        public uint DiskLength { get; set; }
+        public uint DiskLength;
 
-        public uint Length { get; set; }
+        public uint Length;
 
-        public byte Type { get; set; }
+        public byte Type;
 
-        public byte Compression { get; set; }
+        public byte Compression;
 
-        public byte Padding0 { get; set; }
+        public byte Padding0;
 
-        public byte Padding1 { get; set; }
+        public byte Padding1;
 
-        public string? Name { get; set; }
+        /// <remarks>16 bytes</remarks>
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
+        public string? Name;
     }
 }
diff --git a/WAD/LumpInfo.cs b/WAD/LumpInfo.cs
index 4caeb5e..c6e9646 100644
--- a/WAD/LumpInfo.cs
+++ b/WAD/LumpInfo.cs
@@ -1,22 +1,38 @@
+using System.Runtime.InteropServices;
+
 namespace SabreTools.Models.WAD
 {
     /// <see href="https://github.com/RavuAlHemio/hllib/blob/master/HLLib/WADFile.h"/>
     public sealed class LumpInfo
     {
-        public string? Name { get; set; }
+        /// <summary>
+        /// Type 0x42 has no name, type 0x43 does
+        /// </summary>
+        /// <remarks>16 bytes</remarks>
+        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
+        public string? Name;
 
-        public uint Width { get; set; }
+        public uint Width;
 
-        public uint Height { get; set; }
+        public uint Height;
 
-        public uint PixelOffset { get; set; }
+        public uint PixelOffset;
 
-        // 12 bytes of unknown data
+        /// <summary>
+        /// Unknown data
+        /// </summary>
+        /// <remarks>12 bytes</remarks>
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 12)]
+        public byte[]? UnknownData;
 
+        /// <remarks>Width * Height bytes located at PixelOffset</remarks>
         public byte[]? PixelData { get; set; }
 
+        // TODO: Determine what mipmap data looks like
+
         public uint PaletteSize { get; set; }
 
+        /// <remarks>PaletteSize * 3 bytes</remarks>
         public byte[]? PaletteData { get; set; }
     }
 }