- * keypresses. */
-#define GROUP_0 (0 << 16)
-#define GROUP_1 (1 << 16)
-#define GROUP_2 (2 << 16)
-#define GROUP_3 (3 << 16)
+ * keypresses. Two free bits, not used by neither row/col nor keynum,
+ * must be available for use as group bits. The below GROUP_SHIFT
+ * macro definition is based on some prior knowledge of the
+ * matrix_keypad defined KEY() macro internals.
+ */
+#define GROUP_SHIFT 14
+#define GROUP_0 (0 << GROUP_SHIFT)
+#define GROUP_1 (1 << GROUP_SHIFT)
+#define GROUP_2 (2 << GROUP_SHIFT)
+#define GROUP_3 (3 << GROUP_SHIFT)