diff --git a/tools.cmake b/tools.cmake
index 242e33f..c108fab 100644
--- a/tools.cmake
+++ b/tools.cmake
@@ -21,7 +21,7 @@ option(CPPCHECK "Turns on cppcheck processing if it is found." OFF)
 # as the options set.
 macro(clang_tidy)
   if(CLANG_TIDY AND CLANG_TIDY_EXE)
-    set(CMAKE_CXX_CLANG_TIDY ${CLANG_TIDY_EXE} ${ARGN})
+    set(CMAKE_CXX_CLANG_TIDY ${CLANG_TIDY_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()
 
@@ -29,7 +29,7 @@ endmacro()
 # used as the options set.
 macro(include_what_you_use)
   if(IWYU AND IWYU_EXE)
-    set(CMAKE_CXX_INCLUDE_WHAT_YOU_USE ${IWYU_EXE} ${ARGN})
+    set(CMAKE_CXX_INCLUDE_WHAT_YOU_USE ${IWYU_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()
 
@@ -37,7 +37,7 @@ endmacro()
 # options set.
 macro(cppcheck)
   if(CPPCHECK AND CPPCHECK_EXE)
-    set(CMAKE_CXX_CPPCHECK ${CPPCHECK_EXE} ${ARGN})
+    set(CMAKE_CXX_CPPCHECK ${CPPCHECK_EXE} ${ARGN} CACHE STRING "" FORCE)
   endif()
 endmacro()