diff --git a/build.sc b/build.sc
index af0b7b2..b678e4c 100644
--- a/build.sc
+++ b/build.sc
@@ -167,7 +167,7 @@ object core extends BaseJavaModule with BaseMimaModule {
 
 object protobuf extends BaseJavaModule {}
 
-val scala213 = "2.13.16"
+val scala213 = "2.13.18"
 val scalaVersionsMap =
   Map("2.13" -> scala213, "2.12" -> "2.12.20", "3" -> "3.3.7")
 object openapi extends Cross[OpenapiModule](scalaVersionsMap.keys.toList)
diff --git a/modules/openapi/src/alloy/openapi/JsonUnknownMapper.scala b/modules/openapi/src/alloy/openapi/JsonUnknownMapper.scala
index 98bae85..e51f5c7 100644
--- a/modules/openapi/src/alloy/openapi/JsonUnknownMapper.scala
+++ b/modules/openapi/src/alloy/openapi/JsonUnknownMapper.scala
@@ -27,7 +27,6 @@ import alloy.DiscriminatedUnionTrait
 import software.amazon.smithy.jsonschema.Schema
 
 class JsonUnknownMapper() extends JsonSchemaMapper {
-  private final val ADDITIONAL_PROPERTIES = "additionalProperties"
 
   override def updateSchema(
       context: JsonSchemaMapperContext,
diff --git a/modules/openapi/src/alloy/openapi/UntaggedUnion.scala b/modules/openapi/src/alloy/openapi/UntaggedUnion.scala
index 2c79d70..24ddc2b 100644
--- a/modules/openapi/src/alloy/openapi/UntaggedUnion.scala
+++ b/modules/openapi/src/alloy/openapi/UntaggedUnion.scala
@@ -24,7 +24,6 @@ import alloy.UntaggedUnionTrait
 import scala.jdk.CollectionConverters._
 
 class UntaggedUnions() extends JsonSchemaMapper {
-  private final val COMPONENTS = "components"
 
   override def updateSchema(
       shape: Shape,