diff --git a/.github/workflows/documentation.yaml b/.github/workflows/documentation.yaml
index 3ee6d30b..c745d669 100644
--- a/.github/workflows/documentation.yaml
+++ b/.github/workflows/documentation.yaml
@@ -3,7 +3,7 @@ name: Documentation
 on:
   push:
     tags:
-      - '*'
+      - "*"
 
 jobs:
   build:
@@ -12,14 +12,21 @@ jobs:
     steps:
       - uses: actions/checkout@v1
 
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
       - name: Install dependencies
         run: |
           brew install doxygen
           pip3 install jinja2 Pygments
 
       - name: Build
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
         run: |
-          cmake -Hdocumentation -Bbuild
+          cmake -Sdocumentation -Bbuild
           cmake --build build --target GenerateDocs
 
       - name: Publish
diff --git a/.github/workflows/install.yml b/.github/workflows/install.yml
index 997da70f..8dab9a59 100644
--- a/.github/workflows/install.yml
+++ b/.github/workflows/install.yml
@@ -13,25 +13,31 @@ env:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: build and install library
-      run: |
-        cmake -H. -Bbuild -DCMAKE_BUILD_TYPE=Release
-        sudo cmake --build build --target install
-        rm -rf build
-
-    - name: configure
-      run: cmake -Htest -Bbuild -DTEST_INSTALLED_VERSION=1
-
-    - name: build
-      run: cmake --build build --config Debug -j4
-
-    - name: test
-      run: |
-        cd build
-        ctest --build-config Debug
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: build and install library
+        run: |
+          cmake -H. -Bbuild -DCMAKE_BUILD_TYPE=Release
+          sudo cmake --build build --target install
+          rm -rf build
+
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Stest -Bbuild -DTEST_INSTALLED_VERSION=1
+
+      - name: build
+        run: cmake --build build --config Debug -j4
+
+      - name: test
+        run: |
+          cd build
+          ctest --build-config Debug
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
index 2fcbe9cd..d2aa7ce7 100644
--- a/.github/workflows/macos.yml
+++ b/.github/workflows/macos.yml
@@ -13,19 +13,25 @@ env:
 
 jobs:
   build:
-
     runs-on: macos-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: configure
-      run: cmake -Htest -Bbuild -DCMAKE_BUILD_TYPE=Debug
-
-    - name: build
-      run: cmake --build build -j4
-
-    - name: test
-      run: |
-        cd build
-        ctest --build-config Debug
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Stest -Bbuild -DCMAKE_BUILD_TYPE=Debug
+
+      - name: build
+        run: cmake --build build -j4
+
+      - name: test
+        run: |
+          cd build
+          ctest --build-config Debug
diff --git a/.github/workflows/standalone.yml b/.github/workflows/standalone.yml
index 7fe2767e..6827eb48 100644
--- a/.github/workflows/standalone.yml
+++ b/.github/workflows/standalone.yml
@@ -10,17 +10,23 @@ on:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: configure
-      run: cmake -Hstandalone -Bbuild -DCMAKE_BUILD_TYPE=Debug
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Sstandalone -Bbuild -DCMAKE_BUILD_TYPE=Debug -DCMAKE_BUILD_TYPE=Debug
 
-    - name: build
-      run: cmake --build build -j4
+      - name: build
+        run: cmake --build build -j4
 
-    - name: run
-      run: ./build/Greeter
+      - name: run
+        run: ./build/Greeter
diff --git a/.github/workflows/style.yml b/.github/workflows/style.yml
index 48d1fa5b..711900c9 100644
--- a/.github/workflows/style.yml
+++ b/.github/workflows/style.yml
@@ -10,19 +10,25 @@ on:
 
 jobs:
   build:
-
     runs-on: macos-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: Install format dependencies
-      run: |
-        brew install clang-format
-        pip3 install cmake_format==0.6.11 pyyaml
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: Install format dependencies
+        run: |
+          brew install clang-format
+          pip3 install cmake_format==0.6.11 pyyaml
 
-    - name: configure
-      run: cmake -Htest -Bbuild
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Stest -Bbuild
 
-    - name: check style
-      run: cmake --build build --target check-format
+      - name: check style
+        run: cmake --build build --target check-format
diff --git a/.github/workflows/ubuntu.yml b/.github/workflows/ubuntu.yml
index 29d15090..ca2c86d2 100644
--- a/.github/workflows/ubuntu.yml
+++ b/.github/workflows/ubuntu.yml
@@ -14,22 +14,28 @@ env:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: configure
-      run: cmake -Htest -Bbuild -DENABLE_TEST_COVERAGE=1 -DCMAKE_BUILD_TYPE=Debug
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Stest -Bbuild -DENABLE_TEST_COVERAGE=1 -DCMAKE_BUILD_TYPE=Debug
 
-    - name: build
-      run: cmake --build build -j4
+      - name: build
+        run: cmake --build build -j4
 
-    - name: test
-      run: |
-        cd build
-        ctest --build-config Debug
+      - name: test
+        run: |
+          cd build
+          ctest --build-config Debug
 
-    - name: collect code coverage
-      run: bash <(curl -s https://codecov.io/bash) || echo "Codecov did not collect coverage reports"
+      - name: collect code coverage
+        run: bash <(curl -s https://codecov.io/bash) || echo "Codecov did not collect coverage reports"
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 8f6d2b2c..6d6e1b44 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -13,19 +13,25 @@ env:
 
 jobs:
   build:
-
     runs-on: windows-latest
-    
+
     steps:
-    - uses: actions/checkout@v1
-    
-    - name: configure
-      run: cmake -Htest -Bbuild
-
-    - name: build
-      run: cmake --build build --config Debug -j4
-
-    - name: test
-      run: |
-        cd build
-        ctest --build-config Debug
+      - uses: actions/checkout@v1
+
+      - uses: actions/cache@v2
+        with:
+          path: "**/cpm_modules"
+          key: ${{ github.action }}-cpm-modules-${{ hashFiles('**/CMakeLists.txt', '**/*.cmake') }}
+
+      - name: configure
+        env:
+          CPM_SOURCE_CACHE: ${{ github.workspace }}/cpm_modules
+        run: cmake -Stest -Bbuild
+
+      - name: build
+        run: cmake --build build --config Debug -j4
+
+      - name: test
+        run: |
+          cd build
+          ctest --build-config Debug
diff --git a/cmake/CPM.cmake b/cmake/CPM.cmake
index bffba540..7e357412 100644
--- a/cmake/CPM.cmake
+++ b/cmake/CPM.cmake
@@ -1,4 +1,4 @@
-set(CPM_DOWNLOAD_VERSION 0.27.2)
+set(CPM_DOWNLOAD_VERSION 0.28.0)
 
 if(CPM_SOURCE_CACHE)
   set(CPM_DOWNLOAD_LOCATION "${CPM_SOURCE_CACHE}/cpm/CPM_${CPM_DOWNLOAD_VERSION}.cmake")