Gem is failing to install on macos

make
xcrun cc -I. -I. -I/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/universal-darwin11.0 -I. -DRUBY_EXTCONF_H=\"couchbase_config.h\" -I/usr/local/Cellar/libevent/2.0.19/include -I/opt/local/include -I/usr/local/include -I/usr/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -fno-common -g -Os -pipe -fno-common -DENABLE_DTRACE -fno-common -pipe -fno-common -std=c99 -Wall -Wextra -c arguments.c
In file included from arguments.c:18:
couchbase_ext.h:27: error: expected '=', ',', ';', 'asm' or '_attribute_' before 'hrtime_t'
couchbase_ext.h:28: error: expected '=', ',', ';', 'asm' or '_attribute_' before 'gethrtime'
make: *** [arguments.o] Error 1