diff --git a/mac.mk b/mac.mk
index 94afb1d..40f59f8 100644
--- a/mac.mk
+++ b/mac.mk
@@ -25,7 +25,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-YKPERS_VERSION=1.17.3
+YKPERS_VERSION=1.18.1
 YKCLIENT_VERSION=2.15
 CFLAGS="-mmacosx-version-min=10.6 -arch i386 -arch x86_64"
 CHECK=check