diff --git a/common/matrix.h b/common/matrix.h
index d62acb66..d1d14a6e 100644
--- a/common/matrix.h
+++ b/common/matrix.h
@@ -44,7 +44,7 @@ void matrix_init(void);
 /* scan all key states on matrix */
 uint8_t matrix_scan(void);
 /* whether modified from previous scan. used after matrix_scan. */
-bool matrix_is_modified(void);
+bool matrix_is_modified(void) __attribute__ ((deprecated));
 /* whether a swtich is on */
 bool matrix_is_on(uint8_t row, uint8_t col);
 /* matrix state on row */