-AM_CFLAGS="${PTHREAD_CFLAGS} ${GLIB_CFLAGS} ${ASAN_CFLAGS}"
-AM_CXXFLAGS="${PTHREAD_CFLAGS} ${GLIB_CFLAGS} ${ASAN_CXXFLAGS}"
+AM_CFLAGS="-fvisibility=hidden ${PTHREAD_CFLAGS} ${GLIB_CFLAGS} ${ASAN_CFLAGS}"
+AM_CXXFLAGS="-fvisibility=hidden -fvisibility-inlines-hidden ${PTHREAD_CFLAGS} ${GLIB_CFLAGS} ${ASAN_CXXFLAGS}"