diff --git a/.travis.yml b/.travis.yml
index e36e9cd1..922bb7df 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -254,11 +254,13 @@ matrix:
 
   - os: linux
     compiler: clang
-    env: COMPILER=clang++-5.0
+    env:
+      - COMPILER=clang++-4.0
+      - CXXFLAGS=-std=c++17
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty']
-        packages: ['g++-6', 'clang-5.0']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-4.0']
+        packages: ['g++-6', 'clang-4.0']
 
 ################
 # build script #
diff --git a/README.md b/README.md
index fcfe58ca..92d1956a 100644
--- a/README.md
+++ b/README.md
@@ -712,7 +712,7 @@ json j_from_msgpack = json::from_msgpack(v_msgpack);
 Though it's 2016 already, the support for C++11 is still a bit sparse. Currently, the following compilers are known to work:
 
 - GCC 4.9 - 7.1 (and possibly later)
-- Clang 3.4 - 3.9 (and possibly later)
+- Clang 3.4 - 4.0 (and possibly later)
 - Microsoft Visual C++ 2015 / Build Tools 14.0.25123.0 (and possibly later)
 - Microsoft Visual C++ 2017 / Build Tools 15.1.548.43366 (and possibly later)
 
@@ -741,13 +741,12 @@ The following compilers are currently used in continuous integration at [Travis]
 | GCC 5.4.1       | Ubuntu 14.04.5 LTS           | g++-5 (Ubuntu 5.4.1-2ubuntu1~14.04) 5.4.1 20160904 |
 | GCC 6.3.0       | Ubuntu 14.04.5 LTS           | g++-6 (Ubuntu/Linaro 6.3.0-18ubuntu2~14.04) 6.3.0 20170519 |
 | GCC 7.1.0       | Ubuntu 14.04.5 LTS           | g++-7 (Ubuntu 7.1.0-5ubuntu2~14.04) 7.1.0
-| Clang 3.6.0     | Ubuntu 14.04.5 LTS           | clang version 3.6.0 (tags/RELEASE_360/final) |
-| Clang 3.6.1     | Ubuntu 14.04.5 LTS           | clang version 3.6.1 (tags/RELEASE_361/final) |
-| Clang 3.6.2     | Ubuntu 14.04.5 LTS           | clang version 3.6.2 (tags/RELEASE_362/final) |
-| Clang 3.7.0     | Ubuntu 14.04.5 LTS           | clang version 3.7.0 (tags/RELEASE_370/final) |
-| Clang 3.7.1     | Ubuntu 14.04.5 LTS           | clang version 3.7.1 (tags/RELEASE_371/final) |
-| Clang 3.8.0     | Ubuntu 14.04.5 LTS           | clang version 3.8.0 (tags/RELEASE_380/final) |
-| Clang 3.8.1     | Ubuntu 14.04.5 LTS           | clang version 3.8.1 (tags/RELEASE_381/final) |
+| Clang 3.5.0     | Ubuntu 14.04.5 LTS           | clang version 3.5.0-4ubuntu2~trusty2 (tags/RELEASE_350/final) |
+| Clang 3.6.2     | Ubuntu 14.04.5 LTS           | clang version 3.6.2-svn240577-1~exp1 (branches/release_36) |
+| Clang 3.7.1     | Ubuntu 14.04.5 LTS           | clang version 3.7.1-svn253571-1~exp1 (branches/release_37) |
+| Clang 3.8.0     | Ubuntu 14.04.5 LTS           | clang version 3.8.0-2ubuntu3~trusty5 (tags/RELEASE_380/final) |
+| Clang 3.9.1     | Ubuntu 14.04.5 LTS           | clang version 3.9.1-4ubuntu3~14.04.2 (tags/RELEASE_391/rc2) |
+| Clang 4.0.1     | Ubuntu 14.04.5 LTS           | clang version 4.0.1-svn305264-1~exp1 (branches/release_40) |
 | Clang Xcode 6.4 | Darwin Kernel Version 14.3.0 (OSX 10.10.3) | Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) |
 | Clang Xcode 7.3 | Darwin Kernel Version 15.0.0 (OSX 10.10.5) | Apple LLVM version 7.3.0 (clang-703.0.29) |
 | Clang Xcode 8.0 | Darwin Kernel Version 15.6.0 | Apple LLVM version 8.0.0 (clang-800.0.38) |