diff --git a/.travis.yml b/.travis.yml
index d749976..531fce3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -27,9 +27,11 @@ matrix:
 
   include:
     - os: linux
+      compiler: g++
       env: TOOLSET=gcc COMPILER=g++ CXXSTD=c++03
 
     - os: linux
+      compiler: g++-4.7
       env: TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=c++03
       addons:
         apt:
@@ -39,6 +41,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-4.7
       env: TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=c++11
       addons:
         apt:
@@ -48,6 +51,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-4.8
       env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=c++03
       addons:
         apt:
@@ -57,6 +61,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-4.8
       env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=c++11
       addons:
         apt:
@@ -66,6 +71,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-4.9
       env: TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=c++03
       addons:
         apt:
@@ -75,6 +81,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-4.9
       env: TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=c++11
       addons:
         apt:
@@ -84,6 +91,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-5
       env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=c++03
       addons:
         apt:
@@ -93,6 +101,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-5
       env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=c++11
       addons:
         apt:
@@ -102,6 +111,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-5
       env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=c++14
       addons:
         apt:
@@ -111,6 +121,17 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-5
+      env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=c++1z
+      addons:
+        apt:
+          packages:
+            - g++-5
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-6
       env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=c++03
       addons:
         apt:
@@ -120,6 +141,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-6
       env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=c++11
       addons:
         apt:
@@ -129,6 +151,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-6
       env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=c++14
       addons:
         apt:
@@ -138,6 +161,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: g++-6
       env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=c++1z
       addons:
         apt:
@@ -191,9 +215,11 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++03
 
     - os: linux
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++11
 
     - os: linux
@@ -241,6 +267,7 @@ matrix:
             - llvm-toolchain-precise-3.5
 
     - os: linux
+      compiler: clang++-3.6
       env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=c++03
       addons:
         apt:
@@ -251,6 +278,7 @@ matrix:
             - llvm-toolchain-precise-3.6
 
     - os: linux
+      compiler: clang++-3.6
       env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=c++11
       addons:
         apt:
@@ -261,6 +289,7 @@ matrix:
             - llvm-toolchain-precise-3.6
 
     - os: linux
+      compiler: clang++-3.6
       env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=c++14
       addons:
         apt:
@@ -271,6 +300,7 @@ matrix:
             - llvm-toolchain-precise-3.6
 
     - os: linux
+      compiler: clang++-3.6
       env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=c++1z
       addons:
         apt:
@@ -281,6 +311,7 @@ matrix:
             - llvm-toolchain-precise-3.6
 
     - os: linux
+      compiler: clang++-3.7
       env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=c++03
       addons:
         apt:
@@ -291,6 +322,7 @@ matrix:
             - llvm-toolchain-precise-3.7
 
     - os: linux
+      compiler: clang++-3.7
       env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=c++11
       addons:
         apt:
@@ -301,6 +333,7 @@ matrix:
             - llvm-toolchain-precise-3.7
 
     - os: linux
+      compiler: clang++-3.7
       env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=c++14
       addons:
         apt:
@@ -311,6 +344,7 @@ matrix:
             - llvm-toolchain-precise-3.7
 
     - os: linux
+      compiler: clang++-3.7
       env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=c++1z
       addons:
         apt:
@@ -321,6 +355,7 @@ matrix:
             - llvm-toolchain-precise-3.7
 
     - os: linux
+      compiler: clang++-3.8
       env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=c++03
       addons:
         apt:
@@ -331,6 +366,7 @@ matrix:
             - llvm-toolchain-precise-3.8
 
     - os: linux
+      compiler: clang++-3.8
       env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=c++11
       addons:
         apt:
@@ -341,6 +377,7 @@ matrix:
             - llvm-toolchain-precise-3.8
 
     - os: linux
+      compiler: clang++-3.8
       env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=c++14
       addons:
         apt:
@@ -351,6 +388,7 @@ matrix:
             - llvm-toolchain-precise-3.8
 
     - os: linux
+      compiler: clang++-3.8
       env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=c++1z
       addons:
         apt:
@@ -361,6 +399,7 @@ matrix:
             - llvm-toolchain-precise-3.8
 
     - os: linux
+      compiler: clang++-3.9
       env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=c++03
       addons:
         apt:
@@ -371,6 +410,7 @@ matrix:
             - llvm-toolchain-precise-3.9
 
     - os: linux
+      compiler: clang++-3.9
       env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=c++11
       addons:
         apt:
@@ -381,6 +421,7 @@ matrix:
             - llvm-toolchain-precise-3.9
 
     - os: linux
+      compiler: clang++-3.9
       env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=c++14
       addons:
         apt:
@@ -391,6 +432,7 @@ matrix:
             - llvm-toolchain-precise-3.9
 
     - os: linux
+      compiler: clang++-3.9
       env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=c++1z
       addons:
         apt:
@@ -445,15 +487,19 @@ matrix:
             - llvm-toolchain-trusty-4.0
 
     - os: osx
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++03
 
     - os: osx
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++11
 
     - os: osx
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++14
 
     - os: osx
+      compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=c++1z
 
 install: