diff --git a/Modules/CMakeCInformation.cmake b/Modules/CMakeCInformation.cmake
index f6d620f40e..325b11f25e 100644
--- a/Modules/CMakeCInformation.cmake
+++ b/Modules/CMakeCInformation.cmake
@@ -100,7 +100,7 @@ if(NOT CMAKE_MODULE_EXISTS)
   set(CMAKE_SHARED_MODULE_CREATE_C_FLAGS ${CMAKE_SHARED_LIBRARY_CREATE_C_FLAGS})
 endif()
 
-set(CMAKE_C_FLAGS_INIT "$ENV{CFLAGS} ${CMAKE_C_FLAGS_INIT}")
+set(CMAKE_C_FLAGS_INIT "$ENV{CPPFLAGS} $ENV{CFLAGS} ${CMAKE_C_FLAGS_INIT}")
 
 cmake_initialize_per_config_variable(CMAKE_C_FLAGS "Flags used by the C compiler")
 
diff --git a/Modules/CMakeCXXInformation.cmake b/Modules/CMakeCXXInformation.cmake
index dbb4366757..8a0ee288c6 100644
--- a/Modules/CMakeCXXInformation.cmake
+++ b/Modules/CMakeCXXInformation.cmake
@@ -197,7 +197,7 @@ endforeach()
 # on the initial values computed in the platform/*.cmake files
 # use _INIT variables so that this only happens the first time
 # and you can set these flags in the cmake cache
-set(CMAKE_CXX_FLAGS_INIT "$ENV{CXXFLAGS} ${CMAKE_CXX_FLAGS_INIT}")
+set(CMAKE_CXX_FLAGS_INIT "$ENV{CPPFLAGS} $ENV{CXXFLAGS} ${CMAKE_CXX_FLAGS_INIT}")
 
 cmake_initialize_per_config_variable(CMAKE_CXX_FLAGS "Flags used by the CXX compiler")