Index: emu/ser.c
===================================================================
--- emu/ser.c	(revision a2b296e578fac4820601c722f9616fc24f8ef3d4)
+++ emu/ser.c	(revision 49efb91c2113e3a4d2a35361ede72619a0f02e1e)
@@ -32,4 +32,6 @@
 #if defined EMU_WIN
 #define MOU_DIV 64
+#elif defined EMU_OS_X
+#define MOU_DIV 1
 #else
 #define MOU_DIV 4