--- CMakeLists.txt.orig	2021-01-02 18:50:40 UTC
+++ CMakeLists.txt
@@ -52,13 +52,13 @@ set(CMAKE_CXX_STANDARD 14)
 
 if((CMAKE_C_COMPILER_ID STREQUAL "GNU") OR
    (CMAKE_C_COMPILER_ID MATCHES "Clang" AND CMAKE_C_COMPILER_FRONTEND_VARIANT STREQUAL "GNU"))
-    set(CMAKE_C_FLAGS "-Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Wno-unused-parameter -fno-strict-aliasing")
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wmissing-prototypes -Wstrict-prototypes -Wno-unused-parameter -fno-strict-aliasing")
     set(CMAKE_C_FLAGS_DEBUG "-g")
     set(CMAKE_C_FLAGS_RELEASE "-O2")
 endif()
 if((CMAKE_CXX_COMPILER_ID STREQUAL "GNU") OR
    (CMAKE_CXX_COMPILER_ID MATCHES "Clang" AND CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "GNU"))
-    set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused-parameter -fno-strict-aliasing")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-unused-parameter -fno-strict-aliasing")
     set(CMAKE_CXX_FLAGS_DEBUG "-g")
     set(CMAKE_CXX_FLAGS_RELEASE "-O2")
 endif()