diff --git a/.travis.yml b/.travis.yml
index 4f3d5fde..321b8ff3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,15 +13,15 @@ addons:
 
 cache:
   directories:
-    - $HOME/boost_1_64_0/boost
-    - $HOME/boost_1_64_0/stage/64/lib
+    - $HOME/boost_1_65_1/boost
+    - $HOME/boost_1_65_1/stage/64/lib
   cargo: true
 
 install:
   - export CXX="g++-6" CC="gcc-6"
   # Build Boost.
   - wget https://raw.githubusercontent.com/WrinklyNinja/ci-scripts/1.5.0/install_boost.py
-  - python install_boost.py --directory ~ --boost-version 1.64.0 -a 64 -t gcc-6 filesystem locale system
+  - python install_boost.py --directory ~ --boost-version 1.65.1 -a 64 -t gcc-6 filesystem locale system
   # Install packages for generating documentation
   - pip install --user -r docs/requirements.txt
   # Add sphinx-build to PATH
@@ -37,7 +37,7 @@ before_script:
   - mkdir build
   - cd build
   # Link dynamically to the C++ standard library runtime.
-  - cmake .. -DBOOST_ROOT=~/boost_1_64_0 -DBOOST_LIBRARYDIR=~/boost_1_64_0/stage/64/lib
+  - cmake .. -DBOOST_ROOT=~/boost_1_65_1 -DBOOST_LIBRARYDIR=~/boost_1_65_1/stage/64/lib
 
 script:
   - make all
diff --git a/appveyor.yml b/appveyor.yml
index 37027950..10f02598 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -12,9 +12,9 @@ matrix:
   fast_finish: true
 
 cache:
-  - C:\projects\boost_1_61_0\boost
-  - C:\projects\boost_1_61_0\stage\32\lib
-  - C:\projects\boost_1_61_0\stage\64\lib
+  - C:\projects\boost_1_65_1\boost
+  - C:\projects\boost_1_65_1\stage\32\lib
+  - C:\projects\boost_1_65_1\stage\64\lib
 
 environment:
   github_auth_token:
@@ -32,7 +32,7 @@ install:
   - ps: (New-Object Net.WebClient).DownloadFile('https://raw.githubusercontent.com/WrinklyNinja/ci-scripts/1.1.0/install_boost.py', "$env:APPVEYOR_BUILD_FOLDER\install_boost.py")
   - ps: (New-Object Net.WebClient).DownloadFile('https://raw.githubusercontent.com/WrinklyNinja/ci-scripts/1.2.0/delete_old_bintray_versions.py', "$env:APPVEYOR_BUILD_FOLDER\delete_old_bintray_versions.py")
   - ps: if ($env:PLATFORM -eq "Win32") { $env:ADDRESS_MODEL = '32' } else { $env:ADDRESS_MODEL = '64' }
-  - ps: python $env:APPVEYOR_BUILD_FOLDER\install_boost.py -d C:\projects -b 1.61.0 -a $env:ADDRESS_MODEL filesystem locale system
+  - ps: python $env:APPVEYOR_BUILD_FOLDER\install_boost.py -d C:\projects -b 1.65.1 -a $env:ADDRESS_MODEL filesystem locale system
 
 before_build:
   - cd %APPVEYOR_BUILD_FOLDER%
@@ -40,9 +40,9 @@ before_build:
   - cd build
   - ps: |
       if ($env:PLATFORM -eq 'Win32') {
-        cmake .. -G "Visual Studio 14 2015" -DBOOST_ROOT="C:/projects/boost_1_61_0" -DBOOST_LIBRARYDIR="C:/projects/boost_1_61_0/stage/32/lib"
+        cmake .. -G "Visual Studio 14 2015" -DBOOST_ROOT="C:/projects/boost_1_65_1" -DBOOST_LIBRARYDIR="C:/projects/boost_1_65_1/stage/32/lib"
       } else {
-        cmake .. -G "Visual Studio 14 2015 Win64" -DBOOST_ROOT="C:/projects/boost_1_61_0" -DBOOST_LIBRARYDIR="C:/projects/boost_1_61_0/stage/64/lib"
+        cmake .. -G "Visual Studio 14 2015 Win64" -DBOOST_ROOT="C:/projects/boost_1_65_1" -DBOOST_LIBRARYDIR="C:/projects/boost_1_65_1/stage/64/lib"
       }
 
 build: