diff --git a/.travis.yml b/.travis.yml
index 0aaed0b3d..2dd0753ca 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,7 +10,7 @@ script:
 #    - bash <(curl -s https://codecov.io/bash)
 matrix:
   include:
-    - env: SCALA_VERSION=2.12.1 PUBLISH=1
+    - env: SCALA_VERSION=2.12.4 PUBLISH=1
       os: linux
       jdk: oraclejdk8
       sudo: required
@@ -30,10 +30,10 @@ matrix:
       sudo: required
       services:
         - docker
-    - env: SCALA_VERSION=2.12.1 SBT_COURSIER=1
+    - env: SCALA_VERSION=2.12.4 SBT_COURSIER=1
       os: linux
       jdk: oraclejdk8
-    - env: SCALA_VERSION=2.12.1 SBT_SHADING=1
+    - env: SCALA_VERSION=2.12.4 SBT_SHADING=1
       os: linux
       jdk: oraclejdk8
     - env: SCALA_VERSION=2.10.6 SBT_COURSIER=1
@@ -44,7 +44,7 @@ matrix:
     - env: SCALA_VERSION=2.10.6 SBT_SHADING=1
       os: linux
       jdk: oraclejdk8
-    - env: SCALA_VERSION=2.12.1 SCALA_JS=1
+    - env: SCALA_VERSION=2.12.4 SCALA_JS=1
       os: linux
       jdk: oraclejdk8
     - env: SCALA_VERSION=2.11.11 SCALA_JS=1
diff --git a/appveyor.yml b/appveyor.yml
index 33bafab38..69cf4de1d 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -16,18 +16,18 @@ install:
   - git submodule update --init --recursive
 build_script:
   - sbt ++2.11.11 clean compile coreJVM/publishLocal cli/publishLocal
-  - sbt ++2.12.1 http-server/publishLocal
+  - sbt ++2.12.4 http-server/publishLocal
   - sbt ++2.10.6 clean compile
-  - sbt ++2.12.1 coreJVM/publishLocal cache/publishLocal extra/publishLocal # to make the scripted sbt 1.0 tests happy
+  - sbt ++2.12.4 coreJVM/publishLocal cache/publishLocal extra/publishLocal # to make the scripted sbt 1.0 tests happy
   - sbt ++2.10.6 coreJVM/publishLocal cache/publishLocal extra/publishLocal # to make the scripted sbt 0.13 tests happy
 test_script:
   - ps: Start-Job -filepath .\scripts\start-it-auth-server.ps1 -ArgumentList $pwd
   - ps: Start-Sleep -s 15 # wait for the first server to have downloaded its dependencies
   - ps: Start-Job -filepath .\scripts\start-it-no-listing-server.ps1 -ArgumentList $pwd
-  - sbt ++2.12.1 testsJVM/test testsJVM/it:test # Would node be around for testsJS/test?
+  - sbt ++2.12.4 testsJVM/test testsJVM/it:test # Would node be around for testsJS/test?
   - sbt ++2.11.11 testsJVM/test testsJVM/it:test
   - sbt ++2.10.6 testsJVM/test testsJVM/it:test
-  - sbt ++2.12.1 "sbt-coursier/scripted sbt-coursier/simple" sbt-coursier/publishLocal "sbt-shading/scripted sbt-shading/*" # for sbt 1.0
+  - sbt ++2.12.4 "sbt-coursier/scripted sbt-coursier/simple" sbt-coursier/publishLocal "sbt-shading/scripted sbt-shading/*" # for sbt 1.0
   - sbt ++2.10.6 "sbt-coursier/scripted sbt-coursier/*" "sbt-coursier/scripted sbt-coursier-0.13/*" sbt-coursier/publishLocal "sbt-shading/scripted sbt-shading/*" "sbt-shading/scripted sbt-shading-0.13/*" # for sbt 0.13
 cache:
   - '%USERPROFILE%\.ivy2\cache'
diff --git a/core/shared/src/main/scala/coursier/package.scala b/core/shared/src/main/scala/coursier/package.scala
index 20a477f03..08ebfff44 100644
--- a/core/shared/src/main/scala/coursier/package.scala
+++ b/core/shared/src/main/scala/coursier/package.scala
@@ -5,8 +5,10 @@ import coursier.core.{Activation, Parse, Version}
  */
 package object coursier {
 
+  // `extends Serializable` added here-or-there for bin compat while switching from 2.12.1 to 2.12.4
+
   type Dependency = core.Dependency
-  object Dependency {
+  object Dependency extends Serializable {
     def apply(
       module: Module,
       version: String,
@@ -29,7 +31,7 @@ package object coursier {
   }
 
   type Attributes = core.Attributes
-  object Attributes {
+  object Attributes extends Serializable {
     def apply(
       `type`: String = "",
       classifier: String = ""
@@ -47,7 +49,7 @@ package object coursier {
   val Profile = core.Profile
 
   type Module = core.Module
-  object Module {
+  object Module extends Serializable {
     def apply(organization: String, name: String, attributes: Map[String, String] = Map.empty): Module =
       core.Module(organization, name, attributes)
   }
@@ -63,7 +65,7 @@ package object coursier {
   val MavenRepository = maven.MavenRepository
 
   type Resolution = core.Resolution
-  object Resolution {
+  object Resolution extends Serializable {
     val empty = apply()
     def apply(
       rootDependencies: Set[Dependency] = Set.empty,
diff --git a/scripts/travis.sh b/scripts/travis.sh
index d9bb8379b..3aba4d596 100755
--- a/scripts/travis.sh
+++ b/scripts/travis.sh
@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 set -ev
 
-SCALA_VERSION="${SCALA_VERSION:-${TRAVIS_SCALA_VERSION:-2.12.1}}"
+SCALA_VERSION="${SCALA_VERSION:-${TRAVIS_SCALA_VERSION:-2.12.4}}"
 PULL_REQUEST="${PULL_REQUEST:-${TRAVIS_PULL_REQUEST:-false}}"
 BRANCH="${BRANCH:-${TRAVIS_BRANCH:-$(git rev-parse --abbrev-ref HEAD)}}"
 PUBLISH="${PUBLISH:-0}"
@@ -47,7 +47,7 @@ integrationTestsRequirements() {
   # Required for ~/.ivy2/local repo tests
   sbt ++2.11.11 coreJVM/publishLocal cli/publishLocal
 
-  sbt ++2.12.1 http-server/publishLocal
+  sbt ++2.12.4 http-server/publishLocal
 
   # Required for HTTP authentication tests
   launchTestRepo --port 8080 --list-pages
@@ -112,7 +112,14 @@ validateReadme() {
   # check that tut runs fine, and that the README doesn't change after a `sbt tut`
   mv README.md README.md.orig
 
-  sbt ++${SCALA_VERSION} tut
+
+  if is212; then
+    TUT_SCALA_VERSION="2.12.1" # Later versions seem to make tut not see the coursier binaries
+  else
+    TUT_SCALA_VERSION="$SCALA_VERSION"
+  fi
+
+  sbt ++${TUT_SCALA_VERSION} tut
 
   if cmp -s README.md.orig README.md; then
     echo "README.md doesn't change"