diff --git a/.travis.yml b/.travis.yml
index b633faae..b459f5d5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,6 +31,7 @@ matrix:
 
     - os: linux
       compiler: gcc
+      before_install: echo -n | openssl s_client -connect scan.coverity.com:443 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | sudo tee -a /etc/ssl/certs/ca-certificates.crt
       addons:
         apt:
           sources: ['ubuntu-toolchain-r-test']
@@ -43,9 +44,16 @@ matrix:
           build_command_prepend: "make clean ; sudo cp $(which g++-5) $(which g++)"
           build_command: "make"
           branch_pattern: coverity_scan
-          before_install: echo -n | openssl s_client -connect scan.coverity.com:443 | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' | sudo tee -a /etc/ssl/certs/ca-certificates.crt
       env: COMPILER=g++-5
 
+    - os: linux
+      compiler: gcc
+      addons:
+        apt:
+          sources: ['ubuntu-toolchain-r-test']
+          packages: ['g++-6', 'valgrind']
+      env: COMPILER=g++-6
+
     # from https://github.com/travis-ci/travis-ci/issues/6120
     - os: linux
       env:
@@ -61,14 +69,6 @@ matrix:
        - mkdir $HOME/clang-$LLVM_VERSION
        - tar xf $LLVM_ARCHIVE_PATH -C $HOME/clang-$LLVM_VERSION --strip-components 1
 
-#    - os: linux
-#      compiler: gcc
-#      addons:
-#        apt:
-#          sources: ['ubuntu-toolchain-r-test']
-#          packages: ['g++-6', 'valgrind']
-#      env: COMPILER=g++-6
-
     # Clang 3.5 is not able to compile the code,
     # see https://travis-ci.org/nlohmann/json/jobs/126720186
 
diff --git a/README.md b/README.md
index 6ef3539c..9f78413f 100644
--- a/README.md
+++ b/README.md
@@ -74,6 +74,7 @@ The following compilers are currently used in [continuous integration](https://t
 |-----------------|------------------------------|----------------|
 | GCC 4.9.3       | Ubuntu 14.04.4 LTS           | g++-4.9 (Ubuntu 4.9.3-8ubuntu2~14.04) 4.9.3 |
 | GCC 5.3.0       | Ubuntu 14.04.4 LTS           | g++-5 (Ubuntu 5.3.0-3ubuntu1~14.04) 5.3.0 20151204 |
+| GCC 6.1.1       | Ubuntu 14.04.4 LTS           | g++-6 (Ubuntu 6.1.1-3ubuntu11~14.04.1) 6.1.1 20160511 |
 | Clang 3.8.0     | Ubuntu 14.04.4 LTS           | clang version 3.8.0 (tags/RELEASE_380/final) |
 | Clang Xcode 6.1 | Darwin Kernel Version 13.4.0 (OSX 10.9.5) | Apple LLVM version 6.0 (clang-600.0.54) (based on LLVM 3.5svn) |
 | Clang Xcode 6.2 | Darwin Kernel Version 13.4.0 (OSX 10.9.5) | Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn) |
@@ -81,7 +82,7 @@ The following compilers are currently used in [continuous integration](https://t
 | 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 7.1 | Darwin Kernel Version 14.5.0 (OSX 10.10.5) | Apple LLVM version 7.0.0 (clang-700.1.76) |
 | Clang Xcode 7.2 | Darwin Kernel Version 15.0.0 (OSX 10.10.5) | Apple LLVM version 7.0.2 (clang-700.1.81) |
-| Clang Xcode 7.3 | Darwin Kernel Version 14.5.0 (OSX 10.11.1) | Apple LLVM version 7.3.0 (clang-703.0.29) |
+| 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 15.5.0 (OSX 10.11.5) | Apple LLVM version 8.0.0 (clang-800.0.24.1) |
 | Visual Studio 14 2015 | Windows Server 2012 R2 (x64) | Microsoft (R) Build Engine version 14.0.25123.0 |