diff --git a/CMakeLists.txt b/CMakeLists.txt
index a975ef533..4e2f5f9e2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -126,6 +126,7 @@ ENDIF(MSVC)
 IF(UNIX)
 	IF(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
 		ADD_DEFINITIONS(-DFREEBSD)
+		ADD_DEFINITIONS(-D_GLIBCXX_USE_C99)
 		SET(FREEBSD TRUE)
 	ENDIF(CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
 	IF(CMAKE_SYSTEM_NAME MATCHES "Darwin")