diff --git a/build.sbt b/build.sbt
index e89a7febb..050184561 100644
--- a/build.sbt
+++ b/build.sbt
@@ -20,6 +20,22 @@ lazy val core = crossProject
       import com.typesafe.tools.mima.core._
 
       Seq(
+        ProblemFilters.exclude[FinalClassProblem]("coursier.core.Activation$Os"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.core.Version"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.core.Authentication"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.core.VersionInterval"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.Pattern"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.Pattern$Chunk$Opt"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.PropertiesPattern$ChunkOrProperty$Const"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.PropertiesPattern$ChunkOrProperty$Opt"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.PropertiesPattern"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.Pattern$Chunk$Var"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.IvyRepository"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.Pattern$Chunk$Const"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.PropertiesPattern$ChunkOrProperty$Prop"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.ivy.PropertiesPattern$ChunkOrProperty$Var"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.maven.MavenRepository"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.maven.MavenSource"),
         ProblemFilters.exclude[IncompatibleResultTypeProblem]("coursier.package#Resolution.apply$default$9"),
         ProblemFilters.exclude[DirectMissingMethodProblem]("coursier.package#Resolution.apply"),
         ProblemFilters.exclude[IncompatibleResultTypeProblem]("coursier.core.Resolution.copy$default$9"),
@@ -126,6 +142,9 @@ lazy val cache = project
       import com.typesafe.tools.mima.core._
 
       Seq(
+        ProblemFilters.exclude[FinalClassProblem]("coursier.TermDisplay$DownloadInfo"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.TermDisplay$CheckUpdateInfo"),
+        ProblemFilters.exclude[FinalClassProblem]("coursier.util.Base64$B64Scheme"),
         ProblemFilters.exclude[MissingClassProblem]("coursier.TermDisplay$Message$Stop$"),
         ProblemFilters.exclude[MissingClassProblem]("coursier.TermDisplay$Message"),
         ProblemFilters.exclude[MissingClassProblem]("coursier.TermDisplay$Message$"),
diff --git a/cache/src/main/scala/coursier/TermDisplay.scala b/cache/src/main/scala/coursier/TermDisplay.scala
index 89b8b1db4..72b1f56f6 100644
--- a/cache/src/main/scala/coursier/TermDisplay.scala
+++ b/cache/src/main/scala/coursier/TermDisplay.scala
@@ -79,7 +79,7 @@ object TermDisplay {
     def display(): String
   }
 
-  private case class DownloadInfo(
+  private final case class DownloadInfo(
     downloaded: Long,
     previouslyDownloaded: Long,
     length: Option[Long],
@@ -127,7 +127,7 @@ object TermDisplay {
   private def formatTimestamp(ts: Long): String =
     format.format(new Timestamp(ts))
 
-  private case class CheckUpdateInfo(
+  private final case class CheckUpdateInfo(
     currentTimeOpt: Option[Long],
     remoteTimeOpt: Option[Long],
     isDone: Boolean
diff --git a/cache/src/main/scala/coursier/util/Base64.scala b/cache/src/main/scala/coursier/util/Base64.scala
index 0019a80c8..58cf0c888 100644
--- a/cache/src/main/scala/coursier/util/Base64.scala
+++ b/cache/src/main/scala/coursier/util/Base64.scala
@@ -16,7 +16,7 @@ import scala.collection.mutable.ArrayBuilder
 
 object Base64 {
 
-  case class B64Scheme(encodeTable: Array[Char], strictPadding: Boolean = true,
+  final case class B64Scheme(encodeTable: Array[Char], strictPadding: Boolean = true,
                        postEncode: String => String = identity,
                        preDecode: String => String = identity) {
     lazy val decodeTable = {
diff --git a/cli/src/main/scala-2.11/coursier/cli/Bootstrap.scala b/cli/src/main/scala-2.11/coursier/cli/Bootstrap.scala
index 3ae44f51a..071de1c5e 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Bootstrap.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Bootstrap.scala
@@ -11,7 +11,7 @@ import caseapp._
 import coursier.cli.util.Zip
 import coursier.internal.FileUtil
 
-case class Bootstrap(
+final case class Bootstrap(
   @Recurse
     artifactOptions: ArtifactOptions,
   @Recurse
diff --git a/cli/src/main/scala-2.11/coursier/cli/Coursier.scala b/cli/src/main/scala-2.11/coursier/cli/Coursier.scala
index f8e8a9fcf..1cb732438 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Coursier.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Coursier.scala
@@ -7,7 +7,7 @@ import caseapp.core.{ ArgsApp, CommandsMessages }
 import shapeless.union.Union
 
 // Temporary, see comment in Coursier below
-case class CoursierCommandHelper(
+final case class CoursierCommandHelper(
   command: CoursierCommandHelper.U
 ) extends ArgsApp {
   def setRemainingArgs(remainingArgs: Seq[String], extraArgs: Seq[String]): Unit =
diff --git a/cli/src/main/scala-2.11/coursier/cli/Fetch.scala b/cli/src/main/scala-2.11/coursier/cli/Fetch.scala
index 132d1b00e..a541e02f0 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Fetch.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Fetch.scala
@@ -7,7 +7,7 @@ import caseapp._
 
 import scala.language.reflectiveCalls
 
-case class Fetch(
+final case class Fetch(
   @Recurse
     options: FetchOptions
 ) extends App {
diff --git a/cli/src/main/scala-2.11/coursier/cli/Launch.scala b/cli/src/main/scala-2.11/coursier/cli/Launch.scala
index c8bd5f048..074daaba6 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Launch.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Launch.scala
@@ -79,7 +79,7 @@ trait ExtraArgsApp extends caseapp.core.DefaultArgsApp {
     extraArgs1
 }
 
-case class Launch(
+final case class Launch(
   @Recurse
     options: LaunchOptions
 ) extends App with ExtraArgsApp {
diff --git a/cli/src/main/scala-2.11/coursier/cli/Options.scala b/cli/src/main/scala-2.11/coursier/cli/Options.scala
index 72b4100bb..deb6df077 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Options.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Options.scala
@@ -5,7 +5,7 @@ import caseapp.{ HelpMessage => Help, ValueDescription => Value, ExtraName => Sh
 
 import coursier.util.Parse
 
-case class CommonOptions(
+final case class CommonOptions(
   @Help("Keep optional dependencies (Maven)")
     keepOptional: Boolean = false,
   @Help("Download mode (default: missing, that is fetch things missing from cache)")
@@ -94,13 +94,13 @@ case class CommonOptions(
   lazy val classifier0 = classifier.flatMap(_.split(',')).filter(_.nonEmpty)
 }
 
-case class CacheOptions(
+final case class CacheOptions(
   @Help("Cache directory (defaults to environment variable COURSIER_CACHE or ~/.coursier/cache/v1)")
   @Short("C")
     cache: String = Cache.default.toString
 )
 
-case class IsolatedLoaderOptions(
+final case class IsolatedLoaderOptions(
   @Value("target:dependency")
   @Short("I")
     isolated: List[String] = Nil,
@@ -174,7 +174,7 @@ object ArtifactOptions {
   def defaultArtifactTypes = Set("jar", "bundle")
 }
 
-case class ArtifactOptions(
+final case class ArtifactOptions(
   @Help("Artifact types that should be retained (e.g. jar, src, doc, etc.) - defaults to jar,bundle")
   @Value("type1,type2,...")
   @Short("A")
@@ -197,7 +197,7 @@ case class ArtifactOptions(
   }
 }
 
-case class FetchOptions(
+final case class FetchOptions(
   @Help("Fetch source artifacts")
   @Short("S")
     sources: Boolean = false,
@@ -213,7 +213,7 @@ case class FetchOptions(
     common: CommonOptions = CommonOptions()
 )
 
-case class LaunchOptions(
+final case class LaunchOptions(
   @Short("M")
   @Short("main")
     mainClass: String = "",
@@ -226,7 +226,7 @@ case class LaunchOptions(
     common: CommonOptions = CommonOptions()
 )
 
-case class BootstrapOptions(
+final case class BootstrapOptions(
   @Short("M")
   @Short("main")
     mainClass: String = "",
@@ -253,7 +253,7 @@ case class BootstrapOptions(
     common: CommonOptions = CommonOptions()
 )
 
-case class SparkSubmitOptions(
+final case class SparkSubmitOptions(
   @Short("M")
   @Short("main")
   @Help("Main class to be launched (optional if in manifest)")
diff --git a/cli/src/main/scala-2.11/coursier/cli/Resolve.scala b/cli/src/main/scala-2.11/coursier/cli/Resolve.scala
index fd1a78e86..8536de833 100644
--- a/cli/src/main/scala-2.11/coursier/cli/Resolve.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/Resolve.scala
@@ -3,7 +3,7 @@ package cli
 
 import caseapp._
 
-case class Resolve(
+final case class Resolve(
   @Recurse
     common: CommonOptions
 ) extends App {
diff --git a/cli/src/main/scala-2.11/coursier/cli/SparkSubmit.scala b/cli/src/main/scala-2.11/coursier/cli/SparkSubmit.scala
index 4df696265..72f48b777 100644
--- a/cli/src/main/scala-2.11/coursier/cli/SparkSubmit.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/SparkSubmit.scala
@@ -50,7 +50,7 @@ object SparkSubmit {
   * @author Han Ju
   */
 @CommandName("spark-submit")
-case class SparkSubmit(
+final case class SparkSubmit(
   @Recurse
     options: SparkSubmitOptions
 ) extends App with ExtraArgsApp {
diff --git a/cli/src/main/scala-2.11/coursier/cli/spark/Assembly.scala b/cli/src/main/scala-2.11/coursier/cli/spark/Assembly.scala
index 6cc1a59fc..8ddb6b674 100644
--- a/cli/src/main/scala-2.11/coursier/cli/spark/Assembly.scala
+++ b/cli/src/main/scala-2.11/coursier/cli/spark/Assembly.scala
@@ -24,8 +24,8 @@ object Assembly {
       def path: String
     }
 
-    case class Exclude(path: String) extends PathRule
-    case class ExcludePattern(path: Pattern) extends Rule
+    final case class Exclude(path: String) extends PathRule
+    final case class ExcludePattern(path: Pattern) extends Rule
 
     object ExcludePattern {
       def apply(s: String): ExcludePattern =
@@ -34,8 +34,8 @@ object Assembly {
 
     // TODO Accept a separator: Array[Byte] argument in these
     // (to separate content with a line return in particular)
-    case class Append(path: String) extends PathRule
-    case class AppendPattern(path: Pattern) extends Rule
+    final case class Append(path: String) extends PathRule
+    final case class AppendPattern(path: Pattern) extends Rule
 
     object AppendPattern {
       def apply(s: String): AppendPattern =
diff --git a/core/shared/src/main/scala/coursier/core/Activation.scala b/core/shared/src/main/scala/coursier/core/Activation.scala
index 79e980815..1b98abc2d 100644
--- a/core/shared/src/main/scala/coursier/core/Activation.scala
+++ b/core/shared/src/main/scala/coursier/core/Activation.scala
@@ -47,7 +47,7 @@ final case class Activation(
 
 object Activation {
 
-  case class Os(
+  final case class Os(
     arch: Option[String],
     families: Set[String],
     name: Option[String],
diff --git a/core/shared/src/main/scala/coursier/core/Definitions.scala b/core/shared/src/main/scala/coursier/core/Definitions.scala
index 3a5fc6b46..3331b8fc2 100644
--- a/core/shared/src/main/scala/coursier/core/Definitions.scala
+++ b/core/shared/src/main/scala/coursier/core/Definitions.scala
@@ -219,7 +219,7 @@ object Artifact {
   }
 }
 
-case class Authentication(
+final case class Authentication(
   user: String,
   password: String
 ) {
diff --git a/core/shared/src/main/scala/coursier/core/Version.scala b/core/shared/src/main/scala/coursier/core/Version.scala
index 34da4d71d..08b2c3652 100644
--- a/core/shared/src/main/scala/coursier/core/Version.scala
+++ b/core/shared/src/main/scala/coursier/core/Version.scala
@@ -8,7 +8,7 @@ import coursier.core.compatibility._
  *
  *  Same kind of ordering as aether-util/src/main/java/org/eclipse/aether/util/version/GenericVersion.java
  */
-case class Version(repr: String) extends Ordered[Version] {
+final case class Version(repr: String) extends Ordered[Version] {
   lazy val items = Version.items(repr)
   lazy val rawItems: Seq[Version.Item] = {
     val (first, tokens) = Version.Tokenizer(repr)
diff --git a/core/shared/src/main/scala/coursier/core/Versions.scala b/core/shared/src/main/scala/coursier/core/Versions.scala
index d59ecfec9..3512b4ed7 100644
--- a/core/shared/src/main/scala/coursier/core/Versions.scala
+++ b/core/shared/src/main/scala/coursier/core/Versions.scala
@@ -3,10 +3,12 @@ package coursier.core
 import scalaz.{ -\/, \/, \/- }
 import scalaz.Scalaz.ToEitherOps
 
-case class VersionInterval(from: Option[Version],
-                           to: Option[Version],
-                           fromIncluded: Boolean,
-                           toIncluded: Boolean) {
+final case class VersionInterval(
+  from: Option[Version],
+  to: Option[Version],
+  fromIncluded: Boolean,
+  toIncluded: Boolean
+) {
 
   def isValid: Boolean = {
     val fromToOrder =
diff --git a/core/shared/src/main/scala/coursier/ivy/IvyRepository.scala b/core/shared/src/main/scala/coursier/ivy/IvyRepository.scala
index 250fba614..8956db9f2 100644
--- a/core/shared/src/main/scala/coursier/ivy/IvyRepository.scala
+++ b/core/shared/src/main/scala/coursier/ivy/IvyRepository.scala
@@ -8,7 +8,7 @@ import scala.language.higherKinds
 import scalaz._
 import scalaz.Scalaz._
 
-case class IvyRepository(
+final case class IvyRepository(
   pattern: Pattern,
   metadataPatternOpt: Option[Pattern],
   changing: Option[Boolean],
diff --git a/core/shared/src/main/scala/coursier/ivy/Pattern.scala b/core/shared/src/main/scala/coursier/ivy/Pattern.scala
index 98704eff8..f8031e6bb 100644
--- a/core/shared/src/main/scala/coursier/ivy/Pattern.scala
+++ b/core/shared/src/main/scala/coursier/ivy/Pattern.scala
@@ -4,7 +4,7 @@ import scalaz._, Scalaz._
 
 import fastparse.all._
 
-case class PropertiesPattern(chunks: Seq[PropertiesPattern.ChunkOrProperty]) {
+final case class PropertiesPattern(chunks: Seq[PropertiesPattern.ChunkOrProperty]) {
 
   def string: String = chunks.map(_.string).mkString
 
@@ -51,7 +51,7 @@ case class PropertiesPattern(chunks: Seq[PropertiesPattern.ChunkOrProperty]) {
   }
 }
 
-case class Pattern(chunks: Seq[Pattern.Chunk]) {
+final case class Pattern(chunks: Seq[Pattern.Chunk]) {
 
   def +:(chunk: Pattern.Chunk): Pattern =
     Pattern(chunk +: chunks)
@@ -101,17 +101,17 @@ object PropertiesPattern {
   }
 
   object ChunkOrProperty {
-    case class Prop(name: String, alternative: Option[Seq[ChunkOrProperty]]) extends ChunkOrProperty {
+    final case class Prop(name: String, alternative: Option[Seq[ChunkOrProperty]]) extends ChunkOrProperty {
       def string: String =
       s"$${" + name + alternative.fold("")(alt => "-" + alt.map(_.string).mkString) + "}"
     }
-    case class Var(name: String) extends ChunkOrProperty {
+    final case class Var(name: String) extends ChunkOrProperty {
       def string: String = "[" + name + "]"
     }
-    case class Opt(content: ChunkOrProperty*) extends ChunkOrProperty {
+    final case class Opt(content: ChunkOrProperty*) extends ChunkOrProperty {
       def string: String = "(" + content.map(_.string).mkString + ")"
     }
-    case class Const(value: String) extends ChunkOrProperty {
+    final case class Const(value: String) extends ChunkOrProperty {
       def string: String = value
     }
 
@@ -159,13 +159,13 @@ object Pattern {
   }
 
   object Chunk {
-    case class Var(name: String) extends Chunk {
+    final case class Var(name: String) extends Chunk {
       def string: String = "[" + name + "]"
     }
-    case class Opt(content: Chunk*) extends Chunk {
+    final case class Opt(content: Chunk*) extends Chunk {
       def string: String = "(" + content.map(_.string).mkString + ")"
     }
-    case class Const(value: String) extends Chunk {
+    final case class Const(value: String) extends Chunk {
       def string: String = value
     }
 
diff --git a/core/shared/src/main/scala/coursier/maven/MavenRepository.scala b/core/shared/src/main/scala/coursier/maven/MavenRepository.scala
index 796b7f5ca..eaee02d20 100644
--- a/core/shared/src/main/scala/coursier/maven/MavenRepository.scala
+++ b/core/shared/src/main/scala/coursier/maven/MavenRepository.scala
@@ -75,7 +75,7 @@ object MavenRepository {
 
 }
 
-case class MavenRepository(
+final case class MavenRepository(
   root: String,
   changing: Option[Boolean] = None,
   /** Hackish hack for sbt plugins mainly - what this does really sucks */
diff --git a/core/shared/src/main/scala/coursier/maven/MavenSource.scala b/core/shared/src/main/scala/coursier/maven/MavenSource.scala
index fd3c60145..6bdec3c94 100644
--- a/core/shared/src/main/scala/coursier/maven/MavenSource.scala
+++ b/core/shared/src/main/scala/coursier/maven/MavenSource.scala
@@ -2,7 +2,7 @@ package coursier.maven
 
 import coursier.core._
 
-case class MavenSource(
+final case class MavenSource(
   root: String,
   changing: Option[Boolean] = None,
   /** See doc on MavenRepository */
diff --git a/core/shared/src/main/scala/coursier/util/Print.scala b/core/shared/src/main/scala/coursier/util/Print.scala
index c53321981..eb8de860c 100644
--- a/core/shared/src/main/scala/coursier/util/Print.scala
+++ b/core/shared/src/main/scala/coursier/util/Print.scala
@@ -71,7 +71,7 @@ object Print {
       else
         ("", "", "")
 
-    case class Elem(dep: Dependency, excluded: Boolean) {
+    final case class Elem(dep: Dependency, excluded: Boolean) {
 
       lazy val reconciledVersion = resolution.reconciledVersions
         .getOrElse(dep.module, dep.version)
@@ -144,7 +144,7 @@ object Print {
 
     if (reverse) {
 
-      case class Parent(
+      final case class Parent(
         module: Module,
         version: String,
         dependsOn: Module,
diff --git a/http-server/src/main/scala-2.11/coursier/HttpServer.scala b/http-server/src/main/scala-2.11/coursier/HttpServer.scala
index b6cdbbf6d..11e3b732b 100644
--- a/http-server/src/main/scala-2.11/coursier/HttpServer.scala
+++ b/http-server/src/main/scala-2.11/coursier/HttpServer.scala
@@ -16,7 +16,7 @@ import scala.collection.JavaConverters._
 
 import scalaz.concurrent.Task
 
-case class HttpServerApp(
+final case class HttpServerApp(
   @ExtraName("d")
   @ValueDescription("served directory")
     directory: String,
diff --git a/plugin/src/main/scala-2.10/coursier/Credentials.scala b/plugin/src/main/scala-2.10/coursier/Credentials.scala
index c3229fe17..ac55f8579 100644
--- a/plugin/src/main/scala-2.10/coursier/Credentials.scala
+++ b/plugin/src/main/scala-2.10/coursier/Credentials.scala
@@ -15,11 +15,11 @@ sealed abstract class Credentials extends Product with Serializable {
 
 object Credentials {
 
-  case class Direct(user: String, password: String) extends Credentials {
+  final case class Direct(user: String, password: String) extends Credentials {
     override def toString = s"Direct($user, ******)"
   }
 
-  case class FromFile(file: File) extends Credentials {
+  final case class FromFile(file: File) extends Credentials {
 
     private lazy val props = {
       val p = new Properties()
diff --git a/plugin/src/main/scala-2.10/coursier/FallbackDependenciesRepository.scala b/plugin/src/main/scala-2.10/coursier/FallbackDependenciesRepository.scala
index 8d0cc8553..43ea07d77 100644
--- a/plugin/src/main/scala-2.10/coursier/FallbackDependenciesRepository.scala
+++ b/plugin/src/main/scala-2.10/coursier/FallbackDependenciesRepository.scala
@@ -65,7 +65,7 @@ object FallbackDependenciesRepository {
 
 }
 
-case class FallbackDependenciesRepository(
+final case class FallbackDependenciesRepository(
   fallbacks: Map[(Module, String), (URL, Boolean)]
 ) extends Repository {
 
diff --git a/plugin/src/main/scala-2.10/coursier/InterProjectRepository.scala b/plugin/src/main/scala-2.10/coursier/InterProjectRepository.scala
index 88b6e91a1..affb10273 100644
--- a/plugin/src/main/scala-2.10/coursier/InterProjectRepository.scala
+++ b/plugin/src/main/scala-2.10/coursier/InterProjectRepository.scala
@@ -4,7 +4,7 @@ import scala.language.higherKinds
 
 import scalaz.{ -\/, \/-, Monad, EitherT }
 
-case class InterProjectRepository(projects: Seq[Project]) extends Repository {
+final case class InterProjectRepository(projects: Seq[Project]) extends Repository {
 
   private val map = projects
     .map { proj => proj.moduleVersion -> proj }
diff --git a/plugin/src/main/scala-2.10/coursier/ResolutionError.scala b/plugin/src/main/scala-2.10/coursier/ResolutionError.scala
index 951e4d502..cc246c3d9 100644
--- a/plugin/src/main/scala-2.10/coursier/ResolutionError.scala
+++ b/plugin/src/main/scala-2.10/coursier/ResolutionError.scala
@@ -39,11 +39,11 @@ sealed abstract class ResolutionError extends Product with Serializable {
 object ResolutionError {
 
   case object MaximumIterationsReached extends ResolutionError
-  case class UnknownException(ex: Throwable) extends ResolutionError
-  case class UnknownDownloadException(ex: Throwable) extends ResolutionError
-  case class Conflicts(description: String) extends ResolutionError
+  final case class UnknownException(ex: Throwable) extends ResolutionError
+  final case class UnknownDownloadException(ex: Throwable) extends ResolutionError
+  final case class Conflicts(description: String) extends ResolutionError
 
-  case class MetadataDownloadErrors(errors: Seq[(Dependency, Seq[String])]) extends ResolutionError {
+  final case class MetadataDownloadErrors(errors: Seq[(Dependency, Seq[String])]) extends ResolutionError {
     def description(): String = {
 
       def grouped(errs: Seq[String]) =
@@ -86,7 +86,7 @@ object ResolutionError {
     }
   }
 
-  case class DownloadErrors(errors: Seq[FileError]) extends ResolutionError {
+  final case class DownloadErrors(errors: Seq[FileError]) extends ResolutionError {
 
     def description(verbose: Boolean): String = {
 
diff --git a/plugin/src/main/scala-2.10/coursier/Tasks.scala b/plugin/src/main/scala-2.10/coursier/Tasks.scala
index 2dbcc116b..ebd28996c 100644
--- a/plugin/src/main/scala-2.10/coursier/Tasks.scala
+++ b/plugin/src/main/scala-2.10/coursier/Tasks.scala
@@ -250,7 +250,7 @@ object Tasks {
     }
   }
 
-  private case class ResolutionCacheKey(
+  private final case class ResolutionCacheKey(
     project: Project,
     repositories: Seq[Repository],
     userEnabledProfiles: Set[String],
@@ -258,7 +258,7 @@ object Tasks {
     sbtClassifiers: Boolean
   )
 
-  private case class ReportCacheKey(
+  private final case class ReportCacheKey(
     project: Project,
     resolution: Resolution,
     withClassifiers: Boolean,
diff --git a/tests/shared/src/test/scala/coursier/test/TestRepository.scala b/tests/shared/src/test/scala/coursier/test/TestRepository.scala
index 1bbb38024..94e51dcb0 100644
--- a/tests/shared/src/test/scala/coursier/test/TestRepository.scala
+++ b/tests/shared/src/test/scala/coursier/test/TestRepository.scala
@@ -8,7 +8,7 @@ import scala.language.higherKinds
 import scalaz.{ Monad, EitherT }
 import scalaz.Scalaz._
 
-case class TestRepository(projects: Map[(Module, String), Project]) extends Repository {
+final case class TestRepository(projects: Map[(Module, String), Project]) extends Repository {
   val source = new core.Artifact.Source {
     def artifacts(
       dependency: Dependency,
diff --git a/web/src/main/scala/coursier/web/Backend.scala b/web/src/main/scala/coursier/web/Backend.scala
index 64e3511b3..0573bda17 100644
--- a/web/src/main/scala/coursier/web/Backend.scala
+++ b/web/src/main/scala/coursier/web/Backend.scala
@@ -15,11 +15,11 @@ import scala.concurrent.Future
 import scala.scalajs.js
 import js.Dynamic.{ global => g }
 
-case class ResolutionOptions(
+final case class ResolutionOptions(
   followOptional: Boolean = false
 )
 
-case class State(
+final case class State(
   modules: Seq[Dependency],
   repositories: Seq[(String, MavenRepository)],
   options: ResolutionOptions,