diff --git a/src/aimedb/cmd.test.ts b/src/aimedb/decoder.test.ts
similarity index 97%
rename from src/aimedb/cmd.test.ts
rename to src/aimedb/decoder.test.ts
index 2737cce..29edc7a 100644
--- a/src/aimedb/cmd.test.ts
+++ b/src/aimedb/decoder.test.ts
@@ -1,4 +1,4 @@
-import { Decoder } from "./cmd";
+import { Decoder } from "./decoder";
 
 function decode(req) {
   const decoder = new Decoder({});
diff --git a/src/aimedb/cmd.ts b/src/aimedb/decoder.ts
similarity index 51%
rename from src/aimedb/cmd.ts
rename to src/aimedb/decoder.ts
index 95d3627..cc40901 100644
--- a/src/aimedb/cmd.ts
+++ b/src/aimedb/decoder.ts
@@ -94,90 +94,3 @@ export class Decoder extends Transform {
     }
   }
 }
-
-const registerLevels = {
-  none: 0,
-  portal: 1,
-  segaid: 2,
-};
-
-export class Encoder extends Transform {
-  constructor(options) {
-    super({
-      readableObjectMode: true,
-      writableObjectMode: true,
-      ...options,
-    });
-  }
-
-  static init(length) {
-    const buf = Buffer.alloc(length);
-
-    buf.writeUInt16LE(0xa13e, 0x0000); // Magic?
-    buf.writeUInt16LE(0x3087, 0x0002); // ???
-    buf.writeUInt16LE(length, 0x0006);
-
-    return buf;
-  }
-
-  _transform(chunk, encoding, callback) {
-    console.log("Aimedb: Encode", chunk);
-
-    let buf;
-
-    switch (chunk.cmd) {
-      case "hello":
-        buf = Encoder.init(0x0020);
-        buf.writeUInt16LE(0x0065, 0x0004); // cmd code
-        buf.writeUInt16LE(chunk.status, 0x0008);
-
-        break;
-
-      case "campaign":
-        // Still figuring this out...
-
-        buf = Encoder.init(0x0200);
-        buf.writeUInt16LE(0x000c, 0x0004); // cmd code
-        buf.writeUInt16LE(chunk.status, 0x0008);
-
-        // Campaign array starts at 0x20
-        // Element size is 0xA0
-
-        break;
-
-      case "lookup":
-        // -1 aime id means card is not registered
-        // register level does not seem to matter
-
-        buf = Encoder.init(0x0130);
-        buf.writeUInt16LE(0x0010, 0x0004); // cmd code
-        buf.writeUInt16LE(chunk.status, 0x0008);
-        buf.writeInt32LE(chunk.aimeId || -1, 0x0020);
-        buf.writeUInt8(registerLevels[chunk.registerLevel], 0x0024);
-
-        break;
-
-      case "register":
-        buf = Encoder.init(0x0030);
-        buf.writeUInt16LE(0x0006, 0x0004); // cmd code
-        buf.writeUInt16LE(chunk.status, 0x0008);
-        buf.writeInt32LE(chunk.aimeId, 0x0020);
-
-        break;
-
-      case "log":
-        buf = Encoder.init(0x0020);
-        buf.writeUInt16LE(0x000a, 0x0004); // cmd code
-        buf.writeUInt16LE(chunk.status, 0x0008);
-
-        break;
-
-      default:
-        return callback(new Error(`Unimplemented response: ${chunk.cmd}`));
-    }
-
-    console.log("Aimedb: Send", buf);
-
-    return callback(null, buf);
-  }
-}
diff --git a/src/aimedb/encoder.ts b/src/aimedb/encoder.ts
new file mode 100644
index 0000000..291a232
--- /dev/null
+++ b/src/aimedb/encoder.ts
@@ -0,0 +1,88 @@
+import { Transform } from "stream";
+
+const registerLevels = {
+  none: 0,
+  portal: 1,
+  segaid: 2,
+};
+
+export class Encoder extends Transform {
+  constructor(options) {
+    super({
+      readableObjectMode: true,
+      writableObjectMode: true,
+      ...options,
+    });
+  }
+
+  static init(length) {
+    const buf = Buffer.alloc(length);
+
+    buf.writeUInt16LE(0xa13e, 0x0000); // Magic?
+    buf.writeUInt16LE(0x3087, 0x0002); // ???
+    buf.writeUInt16LE(length, 0x0006);
+
+    return buf;
+  }
+
+  _transform(chunk, encoding, callback) {
+    console.log("Aimedb: Encode", chunk);
+
+    let buf;
+
+    switch (chunk.cmd) {
+      case "hello":
+        buf = Encoder.init(0x0020);
+        buf.writeUInt16LE(0x0065, 0x0004); // cmd code
+        buf.writeUInt16LE(chunk.status, 0x0008);
+
+        break;
+
+      case "campaign":
+        // Still figuring this out...
+
+        buf = Encoder.init(0x0200);
+        buf.writeUInt16LE(0x000c, 0x0004); // cmd code
+        buf.writeUInt16LE(chunk.status, 0x0008);
+
+        // Campaign array starts at 0x20
+        // Element size is 0xA0
+
+        break;
+
+      case "lookup":
+        // -1 aime id means card is not registered
+        // register level does not seem to matter
+
+        buf = Encoder.init(0x0130);
+        buf.writeUInt16LE(0x0010, 0x0004); // cmd code
+        buf.writeUInt16LE(chunk.status, 0x0008);
+        buf.writeInt32LE(chunk.aimeId || -1, 0x0020);
+        buf.writeUInt8(registerLevels[chunk.registerLevel], 0x0024);
+
+        break;
+
+      case "register":
+        buf = Encoder.init(0x0030);
+        buf.writeUInt16LE(0x0006, 0x0004); // cmd code
+        buf.writeUInt16LE(chunk.status, 0x0008);
+        buf.writeInt32LE(chunk.aimeId, 0x0020);
+
+        break;
+
+      case "log":
+        buf = Encoder.init(0x0020);
+        buf.writeUInt16LE(0x000a, 0x0004); // cmd code
+        buf.writeUInt16LE(chunk.status, 0x0008);
+
+        break;
+
+      default:
+        return callback(new Error(`Unimplemented response: ${chunk.cmd}`));
+    }
+
+    console.log("Aimedb: Send", buf);
+
+    return callback(null, buf);
+  }
+}
diff --git a/src/aimedb/pipeline.ts b/src/aimedb/pipeline.ts
index 42b9ba5..26e726a 100644
--- a/src/aimedb/pipeline.ts
+++ b/src/aimedb/pipeline.ts
@@ -1,8 +1,9 @@
 import * as crypto from "crypto";
 import { pipeline } from "stream";
 
-import { Decoder, Encoder } from "./cmd";
+import { Decoder } from "./decoder";
 import { Deframer } from "./frame";
+import { Encoder } from "./encoder";
 
 const K = Buffer.from("Copyright(C)SEGA", "utf8");