I have a {source root}/pjlib/include/pj/config_site.h with following content: #define PJ_CONFIG_ANDROID 1 #include <pj/config_site_sample.h> A {source root}/user.mak file with following content: export CFLAGS += -fno-stack-protector And following exported variables: export TARGET_ABI=armeabi-v7a Then I run the following commands: ./configure-android --use-ndk-cflags make dep make clean make the last command 'make' outputs so many error that form of error: undefined reference to 'xxxxxx' such as: output/pjlib-test-arm-unknown-linux-androideabi/main.o:../src/pjlib-test/main.c:function main: error: undefined reference to 'pj_str' or output/pjlib-test-arm-unknown-linux-androideabi/activesock.o:../src/pjlib-test/activesock.c:function activesock_test: error: undefined reference to 'pj_log_get_level' I don't have much acknowledge about building process, please give me some help.