diff --git a/third_party/gopt/CMakeLists.txt b/third_party/gopt/CMakeLists.txt
index cba2b2b0be7d6a9363cb73d5d616afe06bb07df2..0b2c7c75bba7773ef52408f8383eab31ecf8452d 100644
--- a/third_party/gopt/CMakeLists.txt
+++ b/third_party/gopt/CMakeLists.txt
@@ -1,2 +1,2 @@
 add_library(gopt STATIC gopt.c)
-set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${core_cflags}")
+set_target_properties(gopt PROPERTIES COMPILE_FLAGS "${core_cflags}")