diff --git a/CMakeLists.txt b/CMakeLists.txt
index 755aad8..6d84ae1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,7 +8,7 @@ set(VERSION 0.1.1)
 option(DEBUG     "compile with debug symbol"    OFF)
 option(BUNDLE_CIVETWEB     "bundle civetweb with uts-server"    OFF)
 
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -D_BSD_SOURCE -D_XOPEN_SOURCE=700")
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99 -D_DEFAULT_SOURCE -D_XOPEN_SOURCE=700")
 
 if(DEBUG)
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O0 -g")