diff --git a/xwords4/common/comtypes.h b/xwords4/common/comtypes.h
index 869ad2cc7..f573b6b39 100644
--- a/xwords4/common/comtypes.h
+++ b/xwords4/common/comtypes.h
@@ -84,6 +84,7 @@ typedef enum {
 
 #define MAX_NUM_PLAYERS 4
 #define PLAYERNUM_NBITS 2
+#define NDEVICES_NBITS 2        /* 1-4, but reduced by 1 fits in 2 bits */
 #define NPLAYERS_NBITS 3
 #define EMPTIED_TRAY_BONUS 50