diff --git a/.ci/azure-build.yml b/.ci/azure-build.yml
index ab0bf069..04ee5d6b 100644
--- a/.ci/azure-build.yml
+++ b/.ci/azure-build.yml
@@ -1,7 +1,7 @@
 steps:
   # Needed on GCC 4.8 docker image for some reason
   - script: mkdir build
-    displalyName: "Make build directory"
+    displayName: "Make build directory"
 
   - task: CMake@1
     inputs:
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7786d9cd..31bbbbb6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,6 +27,8 @@ project(
   LANGUAGES CXX
   VERSION ${VERSION_STRING})
 
+list(APPEND CMAKE_MODULE_PATH "${CLI11_SOURCE_DIR}/cmake")
+
 # Print the version number of CMake if this is the main project
 if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
   message(STATUS "CMake ${CMAKE_VERSION}")
@@ -128,89 +130,9 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
   set_property(GLOBAL PROPERTY USE_FOLDERS ON)
 endif()
 
-# Special target that adds warnings. Is not exported.
-add_library(CLI11_warnings INTERFACE)
+include(CLI11Warnings)
 
-set(unix-warnings -Wall -Wextra -pedantic -Wshadow -Wsign-conversion -Wswitch-enum)
-
-# Clang warnings
-# -Wfloat-equal could be added with Catch::literals and _a usage
-if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-  list(
-    APPEND
-    unix-warnings
-    -Wcast-align
-    -Wimplicit-atomic-properties
-    -Wmissing-declarations
-    -Woverlength-strings
-    -Wshadow
-    -Wstrict-selector-match
-    -Wundeclared-selector)
-  # -Wunreachable-code Doesn't work on Clang 3.4
-endif()
-
-# Buggy in GCC 4.8
-if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
-  list(APPEND unix-warnings -Weffc++)
-endif()
-
-target_compile_options(
-  CLI11_warnings
-  INTERFACE $<$<BOOL:${CLI11_FORCE_LIBCXX}>:-stdlib=libc++>
-            $<$<CXX_COMPILER_ID:MSVC>:/W4
-            $<$<BOOL:${CLI11_WARNINGS_AS_ERRORS}>:/WX>>
-            $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:${unix-warnings}
-            $<$<BOOL:${CLI11_WARNINGS_AS_ERRORS}>:-Werror>>)
-
-if(NOT CMAKE_VERSION VERSION_LESS 3.13)
-  target_link_options(CLI11_warnings INTERFACE $<$<BOOL:${CLI11_FORCE_LIBCXX}>:-stdlib=libc++>)
-endif()
-
-# To see in IDE, headers must be listed for target
-set(MAYBE_CONFIGURE_DEPENDS "")
-if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME AND NOT CMAKE_VERSION VERSION_LESS 3.12)
-  list(INSERT MAYBE_CONFIGURE_DEPENDS 0 CONFIGURE_DEPENDS)
-endif()
-
-file(GLOB CLI11_headers ${MAYBE_CONFIGURE_DEPENDS} "${PROJECT_SOURCE_DIR}/include/CLI/*.hpp")
-file(GLOB CLI11_impl_headers ${MAYBE_CONFIGURE_DEPENDS}
-     "${PROJECT_SOURCE_DIR}/include/CLI/impl/*.hpp")
-
-if(CLI11_PRECOMPILED)
-  # Create static lib
-  file(GLOB CLI11_precompile_sources "${PROJECT_SOURCE_DIR}/src/*.cpp")
-  add_library(CLI11 STATIC ${CLI11_headers} ${CLI11_impl_headers} ${CLI11_precompile_sources})
-  target_compile_definitions(CLI11 PUBLIC -DCLI11_COMPILE)
-
-  set(PUBLIC_OR_INTERFACE PUBLIC)
-else()
-  add_library(CLI11 INTERFACE)
-  set(PUBLIC_OR_INTERFACE INTERFACE)
-endif()
-
-# Allow IDE's to group targets into folders
-add_library(CLI11::CLI11 ALIAS CLI11) # for add_subdirectory calls
-
-# Duplicated because CMake adds the current source dir if you don't.
-target_include_directories(
-  CLI11 ${PUBLIC_OR_INTERFACE} $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
-  $<INSTALL_INTERFACE:include>)
-
-if(CMAKE_VERSION VERSION_LESS 3.8)
-  # This might not be a complete list
-  target_compile_features(
-    CLI11
-    INTERFACE cxx_lambdas
-              cxx_nullptr
-              cxx_override
-              cxx_range_for
-              cxx_right_angle_brackets
-              cxx_strong_enums
-              cxx_constexpr
-              cxx_auto_type)
-else()
-  target_compile_features(CLI11 INTERFACE cxx_std_11)
-endif()
+add_subdirectory(src)
 
 # Allow tests to be run on CUDA
 if(CLI11_CUDA_TESTS)
@@ -222,13 +144,6 @@ endif()
 
 # This folder should be installed
 if(CLI11_INSTALL)
-  install(FILES ${CLI11_headers} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/CLI")
-  if(NOT CLI11_COMPILE)
-    install(FILES ${CLI11_impl_headers} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/CLI/impl")
-  endif()
-
-  # Make an export target
-  install(TARGETS CLI11 EXPORT CLI11Targets)
 
   # Use find_package on the installed package
   # Since we have no custom code, we can directly write this
@@ -261,42 +176,6 @@ if(CLI11_INSTALL)
   export(PACKAGE CLI11)
 endif()
 
-if(CLI11_SINGLE_FILE)
-  # Single file test
-  if(CMAKE_VERSION VERSION_LESS 3.12)
-    find_package(PythonInterp REQUIRED)
-    add_executable(Python::Interpreter IMPORTED)
-    set_target_properties(Python::Interpreter PROPERTIES IMPORTED_LOCATION "${PYTHON_EXECUTABLE}"
-                                                         VERSION "${PYTHON_VERSION_STRING}")
-  else()
-    find_package(
-      Python
-      COMPONENTS Interpreter
-      REQUIRED)
-  endif()
-
-  file(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/include")
-  add_custom_command(
-    OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/include/CLI11.hpp"
-    COMMAND
-      Python::Interpreter "${CMAKE_CURRENT_SOURCE_DIR}/scripts/MakeSingleHeader.py"
-      ${CLI11_headers} ${CLI11_impl_headers} --main "${CMAKE_CURRENT_SOURCE_DIR}/CLI11.hpp.in"
-      --output "${CMAKE_CURRENT_BINARY_DIR}/include/CLI11.hpp" --version "${CLI11_VERSION}"
-    DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/include/CLI/CLI.hpp" ${CLI11_headers}
-            ${CLI11_impl_headers})
-  add_custom_target(CLI11-generate-single-file ALL
-                    DEPENDS "${CMAKE_CURRENT_BINARY_DIR}/include/CLI11.hpp")
-  set_property(TARGET CLI11-generate-single-file PROPERTY FOLDER "Scripts")
-  install(FILES "${CMAKE_CURRENT_BINARY_DIR}/include/CLI11.hpp" DESTINATION include)
-  add_library(CLI11_SINGLE INTERFACE)
-  target_link_libraries(CLI11_SINGLE INTERFACE CLI11)
-  add_dependencies(CLI11_SINGLE CLI11-generate-single-file)
-  target_compile_definitions(CLI11_SINGLE INTERFACE -DCLI11_SINGLE_FILE)
-  target_include_directories(
-    CLI11_SINGLE INTERFACE $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include/>
-                           $<INSTALL_INTERFACE:include>)
-endif()
-
 if(CLI11_BUILD_TESTS)
   include(CTest)
   add_subdirectory(tests)
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 7540a2ea..c519e153 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -110,7 +110,7 @@ jobs:
           containerImage: gcc:8
           cli11.std: 17
         gcc4.8:
-          containerImage: gcc:4.8
+          containerImage: helics/buildenv:gcc4-8-builder
           cli11.std: 11
           cli11.options:
         clang3.4:
diff --git a/cmake/CLI11Warnings.cmake b/cmake/CLI11Warnings.cmake
new file mode 100644
index 00000000..8b4b499d
--- /dev/null
+++ b/cmake/CLI11Warnings.cmake
@@ -0,0 +1,37 @@
+# Special target that adds warnings. Is not exported.
+add_library(CLI11_warnings INTERFACE)
+
+set(unix-warnings -Wall -Wextra -pedantic -Wshadow -Wsign-conversion -Wswitch-enum)
+
+# Clang warnings
+# -Wfloat-equal could be added with Catch::literals and _a usage
+if(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+  list(
+    APPEND
+    unix-warnings
+    -Wcast-align
+    -Wimplicit-atomic-properties
+    -Wmissing-declarations
+    -Woverlength-strings
+    -Wshadow
+    -Wstrict-selector-match
+    -Wundeclared-selector)
+  # -Wunreachable-code Doesn't work on Clang 3.4
+endif()
+
+# Buggy in GCC 4.8
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.9)
+  list(APPEND unix-warnings -Weffc++)
+endif()
+
+target_compile_options(
+  CLI11_warnings
+  INTERFACE $<$<BOOL:${CLI11_FORCE_LIBCXX}>:-stdlib=libc++>
+            $<$<CXX_COMPILER_ID:MSVC>:/W4
+            $<$<BOOL:${CLI11_WARNINGS_AS_ERRORS}>:/WX>>
+            $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:${unix-warnings}
+            $<$<BOOL:${CLI11_WARNINGS_AS_ERRORS}>:-Werror>>)
+
+if(NOT CMAKE_VERSION VERSION_LESS 3.13)
+  target_link_options(CLI11_warnings INTERFACE $<$<BOOL:${CLI11_FORCE_LIBCXX}>:-stdlib=libc++>)
+endif()
diff --git a/conanfile.py b/conanfile.py
index 377cd014..9dc6ce3a 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -27,6 +27,7 @@ class CLI11Conan(ConanFile):
         "LICENSE",
         "README.md",
         "include/*",
+        "src/*",
         "extern/*",
         "cmake/*",
         "CMakeLists.txt",
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index e124df67..131a9fd0 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -1,5 +1,5 @@
 function(add_cli_exe T)
-  add_executable(${T} ${ARGN} ${CLI11_headers})
+  add_executable(${T} ${ARGN})
   target_link_libraries(${T} PUBLIC CLI11)
   set_property(TARGET ${T} PROPERTY FOLDER "Examples")
   if(CLI11_FORCE_LIBCXX)
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
new file mode 100644
index 00000000..341cae42
--- /dev/null
+++ b/src/CMakeLists.txt
@@ -0,0 +1,120 @@
+set(CLI11_headerLoc "${PROJECT_SOURCE_DIR}/include/CLI")
+
+set(CLI11_headers
+    ${CLI11_headerLoc}/App.hpp
+    ${CLI11_headerLoc}/CLI.hpp
+    ${CLI11_headerLoc}/Config.hpp
+    ${CLI11_headerLoc}/ConfigFwd.hpp
+    ${CLI11_headerLoc}/Error.hpp
+    ${CLI11_headerLoc}/Formatter.hpp
+    ${CLI11_headerLoc}/FormatterFwd.hpp
+    ${CLI11_headerLoc}/Macros.hpp
+    ${CLI11_headerLoc}/Option.hpp
+    ${CLI11_headerLoc}/Split.hpp
+    ${CLI11_headerLoc}/StringTools.hpp
+    ${CLI11_headerLoc}/Timer.hpp
+    ${CLI11_headerLoc}/TypeTools.hpp
+    ${CLI11_headerLoc}/Validators.hpp
+    ${CLI11_headerLoc}/Version.hpp)
+
+set(CLI11_implLoc "${PROJECT_SOURCE_DIR}/include/CLI/impl")
+
+set(CLI11_impl_headers
+    ${CLI11_implLoc}/App_inl.hpp
+    ${CLI11_implLoc}/Config_inl.hpp
+    ${CLI11_implLoc}/Formatter_inl.hpp
+    ${CLI11_implLoc}/Option_inl.hpp
+    ${CLI11_implLoc}/Split_inl.hpp
+    ${CLI11_implLoc}/StringTools_inl.hpp
+    ${CLI11_implLoc}/Validators_inl.hpp)
+
+if(CLI11_PRECOMPILED)
+  # Create static lib
+  file(GLOB CLI11_precompile_sources "${PROJECT_SOURCE_DIR}/src/*.cpp")
+  add_library(CLI11 STATIC ${CLI11_headers} ${CLI11_impl_headers} ${CLI11_precompile_sources})
+  target_compile_definitions(CLI11 PUBLIC -DCLI11_COMPILE)
+
+  set(PUBLIC_OR_INTERFACE PUBLIC)
+else()
+  add_library(CLI11 INTERFACE)
+  if(CMAKE_VERSION VERSION_GREATER 3.19)
+    # This is only useful for visual studio and other IDE builds
+    target_sources(CLI11 PRIVATE ${CLI11_headers} ${CLI11_impl_headers})
+  endif()
+
+  set(PUBLIC_OR_INTERFACE INTERFACE)
+endif()
+
+# Allow IDE's to group targets into folders
+add_library(CLI11::CLI11 ALIAS CLI11) # for add_subdirectory calls
+
+# Duplicated because CMake adds the current source dir if you don't.
+target_include_directories(
+  CLI11 ${PUBLIC_OR_INTERFACE} $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
+  $<INSTALL_INTERFACE:include>)
+
+if(CMAKE_VERSION VERSION_LESS 3.8)
+  # This might not be a complete list
+  target_compile_features(
+    CLI11
+    INTERFACE cxx_lambdas
+              cxx_nullptr
+              cxx_override
+              cxx_range_for
+              cxx_right_angle_brackets
+              cxx_strong_enums
+              cxx_constexpr
+              cxx_auto_type)
+else()
+  target_compile_features(CLI11 INTERFACE cxx_std_11)
+endif()
+
+if(CLI11_SINGLE_FILE)
+  # Single file test
+  if(CMAKE_VERSION VERSION_LESS 3.12)
+    find_package(PythonInterp REQUIRED)
+    add_executable(Python::Interpreter IMPORTED)
+    set_target_properties(Python::Interpreter PROPERTIES IMPORTED_LOCATION "${PYTHON_EXECUTABLE}"
+                                                         VERSION "${PYTHON_VERSION_STRING}")
+  else()
+    find_package(
+      Python
+      COMPONENTS Interpreter
+      REQUIRED)
+  endif()
+
+  file(MAKE_DIRECTORY "${PROJECT_BINARY_DIR}/include")
+  add_custom_command(
+    OUTPUT "${PROJECT_BINARY_DIR}/include/CLI11.hpp"
+    COMMAND
+      Python::Interpreter "${PROJECT_SOURCE_DIR}/scripts/MakeSingleHeader.py" ${CLI11_headers}
+      ${CLI11_impl_headers} --main "${PROJECT_SOURCE_DIR}/CLI11.hpp.in" --output
+      "${PROJECT_BINARY_DIR}/include/CLI11.hpp" --version "${CLI11_VERSION}"
+    DEPENDS "${PROJECT_SOURCE_DIR}/include/CLI/CLI.hpp" ${CLI11_headers} ${CLI11_impl_headers})
+  add_custom_target(CLI11-generate-single-file ALL
+                    DEPENDS "${PROJECT_BINARY_DIR}/include/CLI11.hpp")
+  set_property(TARGET CLI11-generate-single-file PROPERTY FOLDER "Scripts")
+  if(CLI11_INSTALL)
+    install(FILES "${PROJECT_BINARY_DIR}/include/CLI11.hpp"
+            DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
+  endif()
+  add_library(CLI11_SINGLE INTERFACE)
+  target_link_libraries(CLI11_SINGLE INTERFACE CLI11)
+  add_dependencies(CLI11_SINGLE CLI11-generate-single-file)
+  target_compile_definitions(CLI11_SINGLE INTERFACE -DCLI11_SINGLE_FILE)
+  target_include_directories(
+    CLI11_SINGLE INTERFACE $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include/>
+                           $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
+endif()
+
+if(CLI11_INSTALL)
+
+  # Make an export target
+  install(TARGETS CLI11 EXPORT CLI11Targets)
+  if(NOT CLI11_SINGLE_FILE)
+    install(FILES ${CLI11_headers} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/CLI")
+    if(NOT CLI11_COMPILE)
+      install(FILES ${CLI11_impl_headers} DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}/CLI/impl")
+    endif()
+  endif()
+endif()
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 80c4f6a8..7d89e128 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,5 +1,3 @@
-list(APPEND CMAKE_MODULE_PATH "${CLI11_SOURCE_DIR}/cmake")
-
 if(CLI11_SANITIZERS)
   message(STATUS "Using arsenm/sanitizers-cmake")
   FetchContent_Declare(
@@ -109,7 +107,7 @@ foreach(T IN LISTS CLI11_TESTS)
   if(CLI11_CUDA_TESTS)
     set_property(SOURCE ${T}.cpp PROPERTY LANGUAGE CUDA)
   endif()
-  add_executable(${T} ${T}.cpp ${CLI11_headers})
+  add_executable(${T} ${T}.cpp)
   add_sanitizers(${T})
   if(NOT CLI11_CUDA_TESTS)
     target_link_libraries(${T} PRIVATE CLI11_warnings)
@@ -126,7 +124,7 @@ foreach(T IN LISTS CLI11_TESTS)
 endforeach()
 
 foreach(T IN LISTS CLI11_MULTIONLY_TESTS)
-  add_executable(${T} ${T}.cpp ${CLI11_headers})
+  add_executable(${T} ${T}.cpp)
   add_sanitizers(${T})
   target_link_libraries(${T} PUBLIC CLI11)
   add_catch_test(${T})