diff --git a/conan/tools/cmake/toolchain.py b/conan/tools/cmake/toolchain.py
index 0c2b81b3ee2..207ae344654 100644
--- a/conan/tools/cmake/toolchain.py
+++ b/conan/tools/cmake/toolchain.py
@@ -469,10 +469,10 @@ def context(self):
 
 class CMakeFlagsInitBlock(Block):
     template = textwrap.dedent("""
-        set(CMAKE_CXX_FLAGS_INIT "${CONAN_CXX_FLAGS}" CACHE STRING "" FORCE)
-        set(CMAKE_C_FLAGS_INIT "${CONAN_C_FLAGS}" CACHE STRING "" FORCE)
-        set(CMAKE_SHARED_LINKER_FLAGS_INIT "${CONAN_SHARED_LINKER_FLAGS}" CACHE STRING "" FORCE)
-        set(CMAKE_EXE_LINKER_FLAGS_INIT "${CONAN_EXE_LINKER_FLAGS}" CACHE STRING "" FORCE)
+        set(CMAKE_CXX_FLAGS_INIT "${CMAKE_CXX_FLAGS_INIT} ${CONAN_CXX_FLAGS}")
+        set(CMAKE_C_FLAGS_INIT "${CMAKE_C_FLAGS_INIT} ${CONAN_C_FLAGS}")
+        set(CMAKE_SHARED_LINKER_FLAGS_INIT "${CMAKE_SHARED_LINKER_FLAGS_INIT} ${CONAN_SHARED_LINKER_FLAGS}")
+        set(CMAKE_EXE_LINKER_FLAGS_INIT "${CMAKE_EXE_LINKER_FLAGS_INIT} ${CONAN_EXE_LINKER_FLAGS}")
         """)