diff --git a/contrib/fb303/cpp/Makefile.am b/contrib/fb303/cpp/Makefile.am
index 17579c1..748d329 100644
--- a/contrib/fb303/cpp/Makefile.am
+++ b/contrib/fb303/cpp/Makefile.am
@@ -68,7 +68,7 @@
 
 # Set up Thrift specific activity here.
 # We assume that a <name>+types.cpp will always be built from <name>.thrift.
-$(eval $(call thrift_template,.,../if/fb303.thrift,-I $(thrift_home)/share  --gen cpp ))
+$(eval $(call thrift_template,.,../if/fb303.thrift,-I $(thrift_home)/share  --gen cpp:pure_enums ))
 
 include_fb303dir = $(includedir)/thrift/fb303
 include_fb303_HEADERS = FacebookBase.h ServiceTracker.h gen-cpp/FacebookService.h gen-cpp/fb303_constants.h gen-cpp/fb303_types.h