diff --git a/.gitmodules b/.gitmodules
index 42a6fe7..8fba731 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,3 @@
-[submodule "extern/googletest"]
-	path = extern/googletest
-	url = https://github.com/google/googletest.git
 [submodule "extern/doxygen-awesome-css"]
 	path = extern/doxygen-awesome-css
 	url = https://github.com/jothepro/doxygen-awesome-css.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6c25343..f67769a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,10 @@ project(
     LANGUAGES CXX
 )
 
+# dependencies
+include(FetchContent)
+
+
 if (CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
     # folder support for IDEs
     set_property(GLOBAL PROPERTY USE_FOLDERS ON)
@@ -33,15 +37,6 @@ if (CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
     endif ()
 endif ()
 
-# Require out-of-source builds
-file(TO_CMAKE_PATH "${PROJECT_BINARY_DIR}/CMakeLists.txt" LOC_PATH)
-if (EXISTS "${LOC_PATH}")
-    message(
-        FATAL_ERROR
-            "You cannot build in a source directory (or any directory with a CMakeLists.txt file). Please make a build subdirectory. Feel free to remove CMakeCache.txt and CMakeFiles."
-    )
-endif ()
-
 option(KASSERT_WARNINGS_ARE_ERRORS OFF)
 option(KASSERT_BUILD_TESTS OFF)
 
@@ -53,51 +48,44 @@ target_include_directories(kassert_base INTERFACE include)
 
 # set C++ standard to C++17
 target_compile_features(kassert_base INTERFACE cxx_std_17)
-
-list(
-    APPEND
-    KASSERT_WARNING_FLAGS
-    "-Wall"
-    "-Wextra"
-    "-Wconversion"
-    "-Wnon-virtual-dtor"
-    "-Woverloaded-virtual"
-    "-Wshadow"
-    "-Wsign-conversion"
-    "-Wundef"
-    "-Wunreachable-code"
-    "-Wunused"
+add_library(kassert_warnings INTERFACE)
+target_compile_options(
+    kassert_warnings
+    INTERFACE "-Wall"
+              "-Wextra"
+              "-Wconversion"
+              "-Wnon-virtual-dtor"
+              "-Woverloaded-virtual"
+              "-Wshadow"
+              "-Wsign-conversion"
+              "-Wundef"
+              "-Wunreachable-code"
+              "-Wunused"
 )
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-    list(
-        APPEND
-        KASSERT_WARNING_FLAGS
-        "-Wcast-align"
-        "-Wnull-dereference"
-        "-Wpedantic"
-        "-Wextra-semi"
-        "-Wno-gnu-zero-variadic-macro-arguments"
+    target_compile_options(
+        kassert_warnings INTERFACE "-Wcast-align" "-Wnull-dereference" "-Wpedantic" "-Wextra-semi"
+                                   "-Wno-gnu-zero-variadic-macro-arguments"
     )
 endif ()
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    list(
-        APPEND
-        KASSERT_WARNING_FLAGS
-        "-Wcast-align"
-        "-Wnull-dereference"
-        "-Wpedantic"
-        "-Wnoexcept"
-        "-Wsuggest-attribute=const"
-        "-Wsuggest-attribute=noreturn"
-        "-Wsuggest-override"
+    target_compile_options(
+        kassert_warnings
+        INTERFACE "-Wcast-align"
+                  "-Wnull-dereference"
+                  "-Wpedantic"
+                  "-Wnoexcept"
+                  "-Wsuggest-attribute=const"
+                  "-Wsuggest-attribute=noreturn"
+                  "-Wsuggest-override"
     )
 endif ()
 
 # OFF by default.
 if (KASSERT_WARNINGS_ARE_ERRORS)
-    list(APPEND KASSERT_WARNING_FLAGS "-Werror")
+    target_compile_options(kassert_warnings INTERFACE "-Werror")
 endif ()
 
 # Actual library target with compile definitions
@@ -125,5 +113,6 @@ add_library(kassert::kassert ALIAS kassert)
 
 # Testing and examples are only built if this is the main project or if KASSERT_BUILD_TESTS is set (OFF by default)
 if (CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME OR KASSERT_BUILD_TESTS)
+    ensure_googletest()
     add_subdirectory(tests)
 endif ()
diff --git a/extern/googletest b/extern/googletest
deleted file mode 160000
index af29db7..0000000
--- a/extern/googletest
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit af29db7ec28d6df1c7f0f745186884091e602e07
diff --git a/tests/cmake/KassertTestHelper.cmake b/tests/cmake/KassertTestHelper.cmake
index 466cec6..aae4776 100644
--- a/tests/cmake/KassertTestHelper.cmake
+++ b/tests/cmake/KassertTestHelper.cmake
@@ -1,4 +1,4 @@
-add_subdirectory("${PROJECT_SOURCE_DIR}/extern/googletest" "extern/googletest")
+find_package(googletest REQUIRED)
 
 include(GoogleTest)
 
@@ -10,7 +10,7 @@ function (kassert_register_test KASSERT_TARGET_NAME)
     cmake_parse_arguments("KASSERT" "EXCEPTION_MODE" "" "FILES" ${ARGN})
     add_executable(${KASSERT_TARGET_NAME} ${KASSERT_FILES})
     target_link_libraries(${KASSERT_TARGET_NAME} PRIVATE gtest gtest_main gmock kassert_base)
-    target_compile_options(${KASSERT_TARGET_NAME} PRIVATE ${KASSERT_WARNING_FLAGS})
+    target_link_libraries(${KASSERT_TARGET_NAME} PRIVATE kassert_warnings)
     gtest_discover_tests(${KASSERT_TARGET_NAME} WORKING_DIRECTORY ${PROJECT_DIR})
 
     if (KASSERT_EXCEPTION_MODE)