diff --git a/CMakeLists.txt b/CMakeLists.txt
index 27091adf4..7abb5d3df 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,7 +6,7 @@ set(PROJECT_VERSION "3.3.6")
 set(PROJECT_DESC "a lightweight secured socks5 proxy")
 set(PROJECT_URL "https://shadowsocks.org")
 set(PROJECT_ISSUES_URL "https://github.com/shadowsocks/shadowsocks-libev")
-project(${PROJECT_NAME} VERSION ${PROJECT_VERSION})
+project(${PROJECT_NAME} VERSION ${PROJECT_VERSION} LANGUAGES C)
 
 include(GNUInstallDirs)