diff --git a/CMakeLists.txt b/CMakeLists.txt
index 30405359b..475ceab5f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,11 +19,11 @@ OPTION(USE_FORMAT "Use clang-format for checks" OFF)
 
 # These flags are used for all builds
 set(CMAKE_C_STANDARD 11)
-set(CMAKE_C_FLAGS "-Wall")
-set(CMAKE_C_FLAGS_DEBUG "-ggdb -DDEBUGMODE -Werror -fno-omit-frame-pointer")
-set(CMAKE_C_FLAGS_RELWITHDEBINFO "-g -O2 -fno-omit-frame-pointer -DNDEBUG")
-set(CMAKE_C_FLAGS_RELEASE "-O2 -DNDEBUG")
-set(CMAKE_C_FLAGS_MINSIZEREL "-Os -DNDEBUG")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
+set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -ggdb -DDEBUGMODE -Werror -fno-omit-frame-pointer")
+set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -g -O2 -fno-omit-frame-pointer -DNDEBUG")
+set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O2 -DNDEBUG")
+set(CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL} -Os -DNDEBUG")
 add_definitions(-DV_MAJOR=${VERSION_MAJOR} -DV_MINOR=${VERSION_MINOR} -DV_PATCH=${VERSION_PATCH})
 
 # See if we have Git, and use it to fetch current SHA1 hash