diff --git a/cmake/configure.cmake b/cmake/configure.cmake
index 57f6334a..db6307c4 100644
--- a/cmake/configure.cmake
+++ b/cmake/configure.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 if(NOT CMAKE_BUILD_TYPE)
   set(CMAKE_BUILD_TYPE "Release")
 endif(NOT CMAKE_BUILD_TYPE)
diff --git a/cmake/functions.cmake b/cmake/functions.cmake
index e7672113..0c8c3cc5 100644
--- a/cmake/functions.cmake
+++ b/cmake/functions.cmake
@@ -1,4 +1,6 @@
 # ——— Helper function to add & register tests —————————————————————————
+include_guard()
+
 function(ppc_add_test test_name test_src USE_FLAG)
   if(${USE_FLAG})
     add_executable(${test_name} "${PROJECT_SOURCE_DIR}/${test_src}")
diff --git a/cmake/gtest.cmake b/cmake/gtest.cmake
index 7f0f7d44..25b3e68e 100644
--- a/cmake/gtest.cmake
+++ b/cmake/gtest.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 include(ExternalProject)
 
 ExternalProject_Add(
diff --git a/cmake/json.cmake b/cmake/json.cmake
index 30706b15..9c8b726c 100644
--- a/cmake/json.cmake
+++ b/cmake/json.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 include(ExternalProject)
 
 ExternalProject_Add(
diff --git a/cmake/libenvpp.cmake b/cmake/libenvpp.cmake
index c7217a84..c87721c3 100644
--- a/cmake/libenvpp.cmake
+++ b/cmake/libenvpp.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 include(ExternalProject)
 ExternalProject_Add(
   ppc_libenvpp
diff --git a/cmake/modes.cmake b/cmake/modes.cmake
index 946b171f..f62d3de3 100644
--- a/cmake/modes.cmake
+++ b/cmake/modes.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 add_compile_definitions(PPC_PATH_TO_PROJECT="${CMAKE_CURRENT_SOURCE_DIR}")
 
 macro(SUBDIRLIST result curdir)
diff --git a/cmake/mpi.cmake b/cmake/mpi.cmake
index 4922f23b..498b5450 100644
--- a/cmake/mpi.cmake
+++ b/cmake/mpi.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 find_package(MPI REQUIRED COMPONENTS CXX)
 if(NOT MPI_FOUND)
   message(FATAL_ERROR "MPI NOT FOUND")
diff --git a/cmake/onetbb.cmake b/cmake/onetbb.cmake
index 08ef716c..6c559a24 100644
--- a/cmake/onetbb.cmake
+++ b/cmake/onetbb.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 include(ExternalProject)
 
 option(ENABLE_SYSTEM_TBB "Use system TBB instead of bundled version" OFF)
diff --git a/cmake/openmp.cmake b/cmake/openmp.cmake
index a254a88f..ce81da7d 100644
--- a/cmake/openmp.cmake
+++ b/cmake/openmp.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 if(MSVC AND NOT (CMAKE_CXX_COMPILER_ID MATCHES "Clang"))
   set(OpenMP_C_FLAGS
       "/openmp:llvm"
diff --git a/cmake/sanitizers.cmake b/cmake/sanitizers.cmake
index b57359ba..499188fb 100644
--- a/cmake/sanitizers.cmake
+++ b/cmake/sanitizers.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 option(ENABLE_ADDRESS_SANITIZER OFF)
 option(ENABLE_UB_SANITIZER OFF)
 option(ENABLE_LEAK_SANITIZER OFF)
diff --git a/cmake/scoreboard.cmake b/cmake/scoreboard.cmake
index a9f3dc3d..24fdb3d0 100644
--- a/cmake/scoreboard.cmake
+++ b/cmake/scoreboard.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 option(USE_SCOREBOARD OFF)
 if(USE_SCOREBOARD)
   find_package(Python REQUIRED COMPONENTS Interpreter)
diff --git a/cmake/sphinx.cmake b/cmake/sphinx.cmake
index a94b11a4..58474852 100644
--- a/cmake/sphinx.cmake
+++ b/cmake/sphinx.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 option(USE_DOCS OFF)
 if(USE_DOCS)
   set(SPHINXBUILD "sphinx-build")
diff --git a/cmake/stb.cmake b/cmake/stb.cmake
index c737f2f1..9c7cce4d 100644
--- a/cmake/stb.cmake
+++ b/cmake/stb.cmake
@@ -1,3 +1,5 @@
+include_guard()
+
 function(ppc_link_stb exec_func_lib)
   add_library(stb_image STATIC
               ${CMAKE_SOURCE_DIR}/3rdparty/stb_image_wrapper.cpp)