diff --git a/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala b/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
index 5922d0b68..cc8eca64b 100644
--- a/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
+++ b/compiler-plugin/src/main/scala/scalapb/compiler/DescriptorImplicits.scala
@@ -689,9 +689,9 @@ class DescriptorImplicits private[compiler] (
       case SealedOneofStyle.Optional => messageOptions.getSealedOneofExtendsList.asScala.toSeq
     }
 
-    def derives: Seq[String] = messageOptions.getDerivesList.asScala
+    def derives: Seq[String] = messageOptions.getDerivesList.asScala.toSeq
 
-    def sealedOneofDerives: Seq[String] = messageOptions.getSealedOneofDerivesList.asScala
+    def sealedOneofDerives: Seq[String] = messageOptions.getSealedOneofDerivesList.asScala.toSeq
 
     def nestedTypes: Seq[Descriptor] = message.getNestedTypes.asScala.toSeq