diff --git a/README.md b/README.md
index bad24cb..f9042a9 100644
--- a/README.md
+++ b/README.md
@@ -10,3 +10,9 @@ library meant to help reading and writing configuration files.
 - If you're looking for the Bloop codebase, look [here](https://github.com/scalacenter/bloop)
 - If you're looking to contribute, check our [CONTRIBUTING.md](./CONTRIBUTING.md)
 - If you're unfamiliar with Bloop and want to learn more, please check out our full [site](https://scalacenter.github.io/bloop/)
+
+## Binary compatibility
+
+bloop-config uses [unroll](https://github.com/com-lihaoyi/unroll/tree/main) to maintain binary compatibility. 
+If you add an option that breaks binary compatibility import scala.annotation.unroll and annotate the field with @unroll.
+Give the field a reasonable default value.
diff --git a/build.sc b/build.sc
index 337a358..655de24 100644
--- a/build.sc
+++ b/build.sc
@@ -48,9 +48,11 @@ trait CommonPublish extends CiReleaseModule with Mima {
 trait Common extends CrossScalaModule with ScalafmtModule with ScalafixModule {
 
   val jsoniterVersion = "2.4.0"
+  val unrollVersion = "0.1.12"
 
   override def ivyDeps = Agg(
-    ivy"com.github.plokhotnyuk.jsoniter-scala::jsoniter-scala-core::$jsoniterVersion"
+    ivy"com.github.plokhotnyuk.jsoniter-scala::jsoniter-scala-core::$jsoniterVersion",
+    ivy"com.lihaoyi::unroll-annotation:$unrollVersion"
   )
 
   override def compileIvyDeps = Agg(
@@ -58,6 +60,11 @@ trait Common extends CrossScalaModule with ScalafmtModule with ScalafixModule {
   )
 
   override def scalacOptions = Seq("-Ywarn-unused", "-deprecation")
+
+  override def scalacPluginIvyDeps = T {
+    super.scalacPluginIvyDeps() ++
+      Agg(ivy"com.lihaoyi::unroll-plugin:$unrollVersion")
+  }
 }
 
 trait CommonTest extends ScalaModule with TestModule.Munit {
diff --git a/config/src/bloop/config/Config.scala b/config/src/bloop/config/Config.scala
index e0b00cf..223ac0a 100644
--- a/config/src/bloop/config/Config.scala
+++ b/config/src/bloop/config/Config.scala
@@ -1,5 +1,7 @@
 package bloop.config
 
+import scala.annotation.unroll
+
 import bloop.config.PlatformFiles.Path
 import bloop.config.PlatformFiles.emptyPath
 
@@ -164,6 +166,15 @@ object Config {
     val All: List[String] = List(NoModule.id, CommonJSModule.id, ESModule.id)
   }
 
+  sealed abstract class ModuleSplitStyleJS(val id: String)
+  object ModuleSplitStyleJS {
+    case object FewestModules extends ModuleSplitStyleJS("FewestModules")
+    case object SmallestModules extends ModuleSplitStyleJS("SmallestModules")
+    case object SmallModulesFor extends ModuleSplitStyleJS("SmallModulesFor")
+    val All: List[String] =
+      List(FewestModules.id, SmallestModules.id, SmallModulesFor.id)
+  }
+
   case class JsConfig(
       version: String,
       mode: LinkerMode,
@@ -172,7 +183,8 @@ object Config {
       jsdom: Option[Boolean],
       output: Option[Path],
       nodePath: Option[Path],
-      toolchain: List[Path]
+      toolchain: List[Path],
+      @unroll moduleSplitStyle: Option[ModuleSplitStyleJS] = None
   ) extends PlatformConfig
 
   object JsConfig {
diff --git a/config/src/bloop/config/ConfigCodecs.scala b/config/src/bloop/config/ConfigCodecs.scala
index 586f4cc..719bbd4 100644
--- a/config/src/bloop/config/ConfigCodecs.scala
+++ b/config/src/bloop/config/ConfigCodecs.scala
@@ -131,6 +131,48 @@ object ConfigCodecs {
     }
   }
 
+  implicit val codecModuleSplitStyleJS
+      : JsonValueCodec[Config.ModuleSplitStyleJS] = {
+    new JsonValueCodec[Config.ModuleSplitStyleJS] {
+      val nullValue: Config.ModuleSplitStyleJS =
+        null.asInstanceOf[Config.ModuleSplitStyleJS]
+      def encodeValue(x: Config.ModuleSplitStyleJS, out: JsonWriter): Unit = {
+        val str = x match {
+          case Config.ModuleSplitStyleJS.FewestModules =>
+            Config.ModuleSplitStyleJS.FewestModules.id
+          case Config.ModuleSplitStyleJS.SmallestModules =>
+            Config.ModuleSplitStyleJS.SmallestModules.id
+          case Config.ModuleSplitStyleJS.SmallModulesFor =>
+            Config.ModuleSplitStyleJS.SmallModulesFor.id
+        }
+        out.writeVal(str)
+      }
+      def decodeValue(
+          in: JsonReader,
+          default: Config.ModuleSplitStyleJS
+      ): Config.ModuleSplitStyleJS =
+        if (in.isNextToken('"')) {
+          in.rollbackToken()
+          in.readString(null) match {
+            case Config.ModuleSplitStyleJS.FewestModules.id =>
+              Config.ModuleSplitStyleJS.FewestModules
+            case Config.ModuleSplitStyleJS.SmallestModules.id =>
+              Config.ModuleSplitStyleJS.SmallestModules
+            case Config.ModuleSplitStyleJS.SmallModulesFor.id =>
+              Config.ModuleSplitStyleJS.SmallModulesFor
+            case _ =>
+              in.decodeError(
+                s"Expected module split style ${Config.ModuleSplitStyleJS.All
+                    .mkString("'", "', '", "'")}"
+              )
+          }
+        } else {
+          in.rollbackToken()
+          nullValue
+        }
+    }
+  }
+
   implicit val codecJvmConfig: JsonValueCodec[Config.JvmConfig] =
     JsonCodecMaker.makeWithRequiredCollectionFields[Config.JvmConfig]