diff --git a/runelite-script-assembler-plugin/src/main/java/net/runelite/script/AssembleMojo.java b/runelite-script-assembler-plugin/src/main/java/net/runelite/script/AssembleMojo.java
index 8b699c3b14..35d567c267 100644
--- a/runelite-script-assembler-plugin/src/main/java/net/runelite/script/AssembleMojo.java
+++ b/runelite-script-assembler-plugin/src/main/java/net/runelite/script/AssembleMojo.java
@@ -52,56 +52,25 @@ public class AssembleMojo extends AbstractMojo
 	@Parameter(required = true)
 	private File outputDirectory;
 
+	private AssembleMojo(File scriptDirectory, File outputDirectory)
+	{
+		this.scriptDirectory = scriptDirectory;
+		this.outputDirectory = outputDirectory;
+	}
+
 	private final Log log = getLog();
 
-	public static void main(String args[])
+	public static void main(String[] args) throws Exception
 	{
+		if (args.length < 2)
+		{
+			throw new IllegalArgumentException("Usage: inputfile outputfile");
+		}
+
 		File scriptDirectory = new File(args[0]);
 		File outputDirectory = new File(args[1]);
 
-		RuneLiteInstructions instructions = new RuneLiteInstructions();
-		instructions.init();
-
-		Assembler assembler = new Assembler(instructions);
-		ScriptSaver saver = new ScriptSaver();
-
-		int count = 0;
-		File scriptOut = new File(outputDirectory, Integer.toString(IndexType.CLIENTSCRIPT.getNumber()));
-		scriptOut.mkdirs();
-
-		for (File scriptFile : scriptDirectory.listFiles((dir, name) -> name.endsWith(".rs2asm")))
-		{
-			System.out.println("Assembling " + scriptFile);
-
-			try (FileInputStream fin = new FileInputStream(scriptFile))
-			{
-				ScriptDefinition script = assembler.assemble(fin);
-				byte[] packedScript = saver.save(script);
-
-				File targetFile = new File(scriptOut, Integer.toString(script.getId()));
-				Files.write(packedScript, targetFile);
-
-				// Copy hash file
-
-				File hashFile = new File(scriptDirectory, Files.getNameWithoutExtension(scriptFile.getName()) + ".hash");
-				if (hashFile.exists())
-				{
-					Files.copy(hashFile, new File(scriptOut, Integer.toString(script.getId()) + ".hash"));
-				}
-				else if (script.getId() < 10000) // Scripts >=10000 are RuneLite scripts, so they shouldn't have a .hash
-				{
-					System.out.println("Unable to find hash file for " + scriptFile);
-				}
-
-				++count;
-			}
-			catch (IOException ex)
-			{
-				System.out.println("unable to open file " + ex);
-			}
-		}
-
-		System.out.println("Assembled " + count + " scripts");
+		new AssembleMojo(scriptDirectory, outputDirectory).execute();
 	}
 
 	@Override
diff --git a/runelite-script-assembler-plugin/src/main/java/net/runelite/script/IndexMojo.java b/runelite-script-assembler-plugin/src/main/java/net/runelite/script/IndexMojo.java
index e38ddfcd9c..c634171532 100644
--- a/runelite-script-assembler-plugin/src/main/java/net/runelite/script/IndexMojo.java
+++ b/runelite-script-assembler-plugin/src/main/java/net/runelite/script/IndexMojo.java
@@ -48,38 +48,23 @@ public class IndexMojo extends AbstractMojo
 	@Parameter(required = true)
 	private File indexFile;
 
-	public static void main(String args[])
+	private IndexMojo(File archiveOverlayDirectory, File indexFile)
 	{
-		try (DataOutputStream fout = new DataOutputStream(new FileOutputStream(args[1])))
-		{
-			for (File indexFolder : new File(args[0]).listFiles())
-			{
-				if (indexFolder.isDirectory())
-				{
-					int indexId = parseInt(indexFolder.getName());
-					for (File archiveFile : indexFolder.listFiles())
-					{
-						int archiveId;
-						try
-						{
-							archiveId = parseInt(archiveFile.getName());
-						}
-						catch (NumberFormatException ex)
-						{
-							continue;
-						}
+		this.archiveOverlayDirectory = archiveOverlayDirectory;
+		this.indexFile = indexFile;
+	}
 
-						fout.writeInt(indexId << 16 | archiveId);
-					}
-				}
-			}
-
-			fout.writeInt(-1);
-		}
-		catch (IOException ex)
+	public static void main(String[] args) throws Exception
+	{
+		if (args.length < 2)
 		{
-			ex.printStackTrace();
+			throw new IllegalArgumentException("Usage: overlaydir indexfile");
 		}
+
+		File archiveOverlayDirectory = new File(args[0]);
+		File indexFile = new File(args[1]);
+
+		new IndexMojo(archiveOverlayDirectory, indexFile).execute();
 	}
 
 	@Override
@@ -113,7 +98,7 @@ public class IndexMojo extends AbstractMojo
 		}
 		catch (IOException ex)
 		{
-			throw new MojoExecutionException("error build index file", ex);
+			throw new MojoExecutionException("error building index file", ex);
 		}
 	}