diff --git a/cache/src/main/java/net/runelite/cache/io/OutputStream.java b/cache/src/main/java/net/runelite/cache/io/OutputStream.java
index 6f10df2498..751905f4fb 100644
--- a/cache/src/main/java/net/runelite/cache/io/OutputStream.java
+++ b/cache/src/main/java/net/runelite/cache/io/OutputStream.java
@@ -26,6 +26,7 @@ package net.runelite.cache.io;
 
 import com.google.common.base.Preconditions;
 import java.io.IOException;
+import java.io.UnsupportedEncodingException;
 import java.nio.ByteBuffer;
 
 public final class OutputStream extends java.io.OutputStream
@@ -180,7 +181,15 @@ public final class OutputStream extends java.io.OutputStream
 
 	public void writeString(String str)
 	{
-		byte[] b = str.getBytes();
+		byte[] b;
+		try
+		{
+			b = str.getBytes("ISO-8859-1");
+		}
+		catch (UnsupportedEncodingException ex)
+		{
+			throw new RuntimeException(ex);
+		}
 		writeBytes(b);
 		writeByte(0);
 	}
diff --git a/cache/src/test/java/net/runelite/cache/definitions/savers/ScriptSaverTest.java b/cache/src/test/java/net/runelite/cache/definitions/savers/ScriptSaverTest.java
index a4a5ca1b6a..447b392ae3 100644
--- a/cache/src/test/java/net/runelite/cache/definitions/savers/ScriptSaverTest.java
+++ b/cache/src/test/java/net/runelite/cache/definitions/savers/ScriptSaverTest.java
@@ -39,6 +39,7 @@ import org.junit.Test;
 public class ScriptSaverTest
 {
 	private static final String SCRIPT_RESOURCE = "/net/runelite/cache/script/assembler/91.rs2asm";
+	private static final String SCRIPT_RESOURCE_UNICODE = "/net/runelite/cache/script/assembler/Unicode.rs2asm";
 
 	@Test
 	public void testSave() throws IOException
@@ -51,4 +52,15 @@ public class ScriptSaverTest
 		assertEquals(script, loadedScripot);
 	}
 
+	@Test
+	public void testSaveUnicode() throws IOException
+	{
+		Instructions instructions = new Instructions();
+		instructions.init();
+		ScriptDefinition script = new Assembler(instructions).assemble(getClass().getResourceAsStream(SCRIPT_RESOURCE_UNICODE));
+		byte[] saved = new ScriptSaver().save(script);
+		ScriptDefinition loadedScripot = new ScriptLoader().load(42, saved);
+		assertEquals(script, loadedScripot);
+	}
+
 }
diff --git a/cache/src/test/java/net/runelite/cache/io/OutputStreamTest.java b/cache/src/test/java/net/runelite/cache/io/OutputStreamTest.java
index 29dd902168..42bbc238bb 100644
--- a/cache/src/test/java/net/runelite/cache/io/OutputStreamTest.java
+++ b/cache/src/test/java/net/runelite/cache/io/OutputStreamTest.java
@@ -24,7 +24,7 @@
  */
 package net.runelite.cache.io;
 
-import org.junit.Assert;
+import static org.junit.Assert.assertEquals;
 import org.junit.Test;
 
 public class OutputStreamTest
@@ -38,9 +38,22 @@ public class OutputStreamTest
 		os.writeBigSmart(65535);
 
 		InputStream is = new InputStream(os.getArray());
-		Assert.assertEquals(42, is.readBigSmart());
-		Assert.assertEquals(70000, is.readBigSmart());
-		Assert.assertEquals(65535, is.readBigSmart());
+		assertEquals(42, is.readBigSmart());
+		assertEquals(70000, is.readBigSmart());
+		assertEquals(65535, is.readBigSmart());
+	}
+
+	@Test
+	public void testWriteString()
+	{
+		char[] c = new char[]{32, 160};
+		String str = new String(c, 0, c.length);
+
+		OutputStream os = new OutputStream();
+		os.writeString(str);
+
+		// 1 byte length + 32 + 160
+		assertEquals(3, os.getOffset());
 	}
 
 }
diff --git a/cache/src/test/java/net/runelite/cache/script/assembler/AssemblerTest.java b/cache/src/test/java/net/runelite/cache/script/assembler/AssemblerTest.java
index 819937cfb7..0e5dccd4f1 100644
--- a/cache/src/test/java/net/runelite/cache/script/assembler/AssemblerTest.java
+++ b/cache/src/test/java/net/runelite/cache/script/assembler/AssemblerTest.java
@@ -52,7 +52,8 @@ public class AssemblerTest
 		return new String[]
 		{
 			"91.rs2asm",
-			"681.rs2asm"
+			"681.rs2asm",
+			"Unicode.rs2asm"
 		};
 	}
 
diff --git a/cache/src/test/resources/net/runelite/cache/script/assembler/Unicode.rs2asm b/cache/src/test/resources/net/runelite/cache/script/assembler/Unicode.rs2asm
new file mode 100644
index 0000000000..7a10d7ccec
--- /dev/null
+++ b/cache/src/test/resources/net/runelite/cache/script/assembler/Unicode.rs2asm
@@ -0,0 +1,6 @@
+.int_stack_count    0
+.string_stack_count 0
+.int_var_count      0
+.string_var_count   0
+   load_string            ": "
+   return