diff --git a/OpenRA.FileFormats/Exts.cs b/OpenRA.FileFormats/Exts.cs
index 916e458336..2b09647e30 100755
--- a/OpenRA.FileFormats/Exts.cs
+++ b/OpenRA.FileFormats/Exts.cs
@@ -10,10 +10,10 @@
 
 using System;
 using System.Collections.Generic;
+using System.Drawing;
 using System.IO;
 using System.Linq;
 using System.Reflection;
-using System.Drawing;
 
 namespace OpenRA
 {
diff --git a/OpenRA.FileFormats/FileFormats/Format80.cs b/OpenRA.FileFormats/FileFormats/Format80.cs
index a48bc23ece..74be6edd04 100644
--- a/OpenRA.FileFormats/FileFormats/Format80.cs
+++ b/OpenRA.FileFormats/FileFormats/Format80.cs
@@ -9,6 +9,7 @@
 #endregion
 
 using System;
+using System.IO;
 
 namespace OpenRA.FileFormats
 {
@@ -124,24 +125,24 @@ namespace OpenRA.FileFormats
 			}
 		}
 
-		public static int EncodeInto(byte[] src, byte[] dest)
+		public static byte[] Encode(byte[] src)
 		{
 			/* quick & dirty format80 encoder -- only uses raw copy operator, terminated with a zero-run. */
 			/* this does not produce good compression, but it's valid format80 */
 			
-			var destIndex = 0;
 			var ctx = new FastByteReader(src);
+			var ms = new MemoryStream();
 
 			do
 			{
 				var len = Math.Min(ctx.Remaining(), 0x3F);
-				dest[destIndex++] = (byte)(0x80 | len);
-				if (len > 0)
-					ctx.CopyTo(dest, destIndex, len);
+				ms.WriteByte((byte)(0x80 | len));
+				while (len-- > 0)
+					ms.WriteByte(ctx.ReadByte());
 			}
 			while (!ctx.Done());
 
-			return destIndex;
+			return ms.ToArray();
 		}
 	}
 }
diff --git a/OpenRA.FileFormats/Graphics/ShpReader.cs b/OpenRA.FileFormats/Graphics/ShpReader.cs
index c41cd33c08..e734d42b98 100644
--- a/OpenRA.FileFormats/Graphics/ShpReader.cs
+++ b/OpenRA.FileFormats/Graphics/ShpReader.cs
@@ -26,6 +26,8 @@ namespace OpenRA.FileFormats
 
 		public byte[] Image;
 
+		public ImageHeader() { }
+
 		public ImageHeader( BinaryReader reader )
 		{
 			Offset = reader.ReadUInt32();
@@ -35,6 +37,15 @@ namespace OpenRA.FileFormats
 			RefOffset = reader.ReadUInt16();
 			RefFormat = (Format)reader.ReadUInt16();
 		}
+
+		public static readonly int SizeOnDisk = 8;
+
+		public void WriteTo(BinaryWriter writer)
+		{
+			writer.Write(Offset | ((uint)Format << 24));
+			writer.Write((ushort)RefOffset);
+			writer.Write((ushort)RefFormat);
+		}
 	}
 
 	public enum Format
diff --git a/OpenRA.FileFormats/Graphics/ShpWriter.cs b/OpenRA.FileFormats/Graphics/ShpWriter.cs
new file mode 100644
index 0000000000..11e5ec5a94
--- /dev/null
+++ b/OpenRA.FileFormats/Graphics/ShpWriter.cs
@@ -0,0 +1,46 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+
+namespace OpenRA.FileFormats.Graphics
+{
+	// format80-only SHP writer
+
+	public static class ShpWriter
+	{
+		public static void Write(Stream s, int width, int height, IEnumerable<byte[]> frames)
+		{
+			var compressedFrames = frames.Select(f => Format80.Encode(f)).ToArray();
+
+			// note: end-of-file and all-zeroes headers
+			var dataOffset = 14 + (compressedFrames.Length + 2) * ImageHeader.SizeOnDisk;
+
+			using (var bw = new BinaryWriter(s))
+			{
+				bw.Write((ushort)compressedFrames.Length);
+				bw.Write((ushort)0);	// unused
+				bw.Write((ushort)0);	// unused
+				bw.Write((ushort)width);
+				bw.Write((ushort)height);
+				bw.Write((uint)0);		// unused
+
+				foreach (var f in compressedFrames)
+				{
+					var ih = new ImageHeader { Format = Format.Format80, Offset = (uint)dataOffset };
+					dataOffset += f.Length;
+
+					ih.WriteTo(bw);
+				}
+
+				var eof = new ImageHeader { Format = Format.Format80, Offset = (uint)dataOffset };
+				eof.WriteTo(bw);
+
+				var allZeroes = new ImageHeader { };
+				allZeroes.WriteTo(bw);
+
+				foreach (var f in compressedFrames)
+					bw.Write(f);
+			}
+		}
+	}
+}
diff --git a/OpenRA.FileFormats/OpenRA.FileFormats.csproj b/OpenRA.FileFormats/OpenRA.FileFormats.csproj
index 6b27141718..5955859895 100644
--- a/OpenRA.FileFormats/OpenRA.FileFormats.csproj
+++ b/OpenRA.FileFormats/OpenRA.FileFormats.csproj
@@ -66,6 +66,7 @@
     <Compile Include="FieldLoader.cs" />
     <Compile Include="Graphics\IGraphicsDevice.cs" />
     <Compile Include="Graphics\IInputHandler.cs" />
+    <Compile Include="Graphics\ShpWriter.cs" />
     <Compile Include="Graphics\Vertex.cs" />
     <Compile Include="HttpUtil.cs" />
     <Compile Include="Manifest.cs" />