diff --git a/.clang-format b/.clang-format
new file mode 100644
index 000000000..ff2d7a7dd
--- /dev/null
+++ b/.clang-format
@@ -0,0 +1,4 @@
+---
+AccessModifierOffset: -3
+IndentWidth: 3
+...
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 52ddb2e49..d260fba01 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,6 +14,12 @@ if(CMAKE_CXX_STANDARD LESS 17)
    set(CMAKE_CXX_STANDARD 17)
 endif()
 
+if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git")
+   include(GitSubmoduleCheck)
+   git_submodule_check(lib/external/asio)
+   git_submodule_check(lib/infra)
+endif()
+
 include(ElementsConfigCommon)
 
 option(ELEMENTS_BUILD_EXAMPLES "build Elements library examples" ON)
diff --git a/cmake/GitSubmoduleCheck.cmake b/cmake/GitSubmoduleCheck.cmake
new file mode 100644
index 000000000..9e36e992e
--- /dev/null
+++ b/cmake/GitSubmoduleCheck.cmake
@@ -0,0 +1,9 @@
+# https://gist.github.com/scivision/bb1d47a9529e153617414e91ff5390af
+find_package(Git REQUIRED)
+function(git_submodule_check dir)
+   if(NOT EXISTS "${dir}/CMakeLists.txt")
+      execute_process(COMMAND ${GIT_EXECUTABLE} submodule update --init --recursive -- ${dir}
+         WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
+         COMMAND_ERROR_IS_FATAL ANY)
+   endif()
+endfunction()