diff --git a/.github/workflows/coverage.yml b/.github/workflows/coverage.yml
index b0b79f4..09e95e1 100644
--- a/.github/workflows/coverage.yml
+++ b/.github/workflows/coverage.yml
@@ -8,6 +8,8 @@ jobs:
     name: "coverage"
     steps:
     - uses: actions/checkout@v2
+      with:
+        submodules: recursive
     - name: Install lcov by Homebrew
       run: brew install lcov
     - name: Build && Test && Upload
diff --git a/.github/workflows/darwin.yml b/.github/workflows/darwin.yml
index 85a0aeb..07e86ea 100644
--- a/.github/workflows/darwin.yml
+++ b/.github/workflows/darwin.yml
@@ -16,6 +16,8 @@ jobs:
     name: "xcode-${{matrix.config.xcode}}"
     steps:
     - uses: actions/checkout@v2
+      with:
+        submodules: recursive
     - name: Select Xcode
       run: sudo xcode-select --switch "/Applications/Xcode_${{matrix.config.xcode}}.app"
     - name: Build && Test
diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 3f508ac..c785bc7 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -14,6 +14,7 @@ jobs:
         - { os: "ubuntu-20.04", cc: "gcc-8", cxx: "g++-8" }
         - { os: "ubuntu-20.04", cc: "gcc-9", cxx: "g++-9" }
         - { os: "ubuntu-20.04", cc: "gcc-10", cxx: "g++-10" }
+        - { os: "ubuntu-20.04", cc: "clang-7", cxx: "clang++-7" }
         - { os: "ubuntu-20.04", cc: "clang-8", cxx: "clang++-8" }
         - { os: "ubuntu-20.04", cc: "clang-9", cxx: "clang++-9" }
         - { os: "ubuntu-20.04", cc: "clang-10", cxx: "clang++-10" }
@@ -23,6 +24,8 @@ jobs:
       run: sudo apt-get -y install "${{matrix.config.cc}}" "${{matrix.config.cxx}}"
     - name: Checkout
       uses: actions/checkout@v2
+      with:
+        submodules: recursive
     - name: Build && Test
       run: .ci/build_linux.sh
       env: { CC: "${{matrix.config.cc}}", CXX: "${{matrix.config.cxx}}" }
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
index 1c48908..1486034 100644
--- a/.github/workflows/windows.yml
+++ b/.github/workflows/windows.yml
@@ -17,5 +17,7 @@ jobs:
     name: "${{matrix.config.vs}} ${{matrix.config.arch}}"
     steps:
     - uses: actions/checkout@v2
+      with:
+        submodules: recursive
     - name: Build && Test
       run: .ci\build_windows_${{matrix.config.arch}}.bat
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6d64e76..ea8e62b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,8 @@ cmake_minimum_required(VERSION 3.8 FATAL_ERROR)
 
 if(NOT DEFINED PROJECT_NAME)
     set(BUILD_AS_STANDALONE ON)
+else()
+    set(BUILD_AS_STANDALONE OFF)
 endif()
 
 project(vmath.hpp)
@@ -15,6 +17,26 @@ add_library(${PROJECT_NAME}.singles INTERFACE)
 target_compile_features(${PROJECT_NAME}.singles INTERFACE cxx_std_17)
 target_include_directories(${PROJECT_NAME}.singles INTERFACE singles)
 
+target_compile_options(${PROJECT_NAME}
+    INTERFACE
+    $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
+        -Wno-c++98-compat-pedantic
+        -Wno-ctad-maybe-unsupported
+        -Wno-double-promotion
+        -Wno-float-equal
+        -Wno-shadow
+        -Wno-unknown-warning-option>)
+
+target_compile_options(${PROJECT_NAME}.singles
+    INTERFACE
+    $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
+        -Wno-c++98-compat-pedantic
+        -Wno-ctad-maybe-unsupported
+        -Wno-double-promotion
+        -Wno-float-equal
+        -Wno-shadow
+        -Wno-unknown-warning-option>)
+
 if(BUILD_AS_STANDALONE)
     option(BUILD_WITH_UNTESTS "Build with unit tests" ON)
     if(BUILD_WITH_UNTESTS)
diff --git a/README.md b/README.md
index 8629460..db12e12 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@
 ## Requirements
 
 - [gcc](https://www.gnu.org/software/gcc/) **>= 7**
-- [clang](https://clang.llvm.org/) **>= 5.0**
+- [clang](https://clang.llvm.org/) **>= 7**
 - [msvc](https://visualstudio.microsoft.com/) **>= 2017**
 
 ## Installation
diff --git a/untests/CMakeLists.txt b/untests/CMakeLists.txt
index 0220203..cac5ff7 100644
--- a/untests/CMakeLists.txt
+++ b/untests/CMakeLists.txt
@@ -23,15 +23,12 @@ target_link_libraries(${PROJECT_NAME} vmath.hpp.singles)
 target_compile_options(${PROJECT_NAME}
     PRIVATE
     $<$<CXX_COMPILER_ID:MSVC>:
-        /W4>
+        /WX /W4>
     PRIVATE
     $<$<CXX_COMPILER_ID:GNU>:
-        -Wall -Wextra -Wpedantic>
+        -Werror -Wall -Wextra -Wpedantic>
     PRIVATE
     $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
-        -Weverything -Wno-unknown-warning-option
-        -Wconversion -Wimplicit-int-float-conversion
-        -Wno-c++98-compat-pedantic -Wno-ctad-maybe-unsupported
-        -Wno-float-equal -Wno-double-promotion -Wno-shadow-field-in-constructor>)
+        -Werror -Weverything -Wconversion>)
 
 add_test(${PROJECT_NAME} ${PROJECT_NAME})