diff --git a/board/daisy/board.h b/board/daisy/board.h
index 4849259ecc..f06a4cf86a 100644
--- a/board/daisy/board.h
+++ b/board/daisy/board.h
@@ -22,6 +22,9 @@
 
 #define USB_CHARGE_PORT_COUNT 0
 
+/* EC drives 13 outputs to keyboard matrix */
+#define KB_OUTPUTS 13
+
 /* GPIO signal list */
 enum gpio_signal {
 	/* Inputs with interrupt handlers are first for efficiency */
diff --git a/board/snow/board.h b/board/snow/board.h
index 93d219a635..6192fc1ce6 100644
--- a/board/snow/board.h
+++ b/board/snow/board.h
@@ -16,6 +16,9 @@
 
 #define USB_CHARGE_PORT_COUNT 0
 
+/* EC drives 13 outputs to keyboard matrix */
+#define KB_OUTPUTS 13
+
 /* GPIO signal list */
 enum gpio_signal {
 	/* Inputs with interrupt handlers are first for efficiency */
diff --git a/chip/stm32/keyboard_scan.c b/chip/stm32/keyboard_scan.c
index f6b1576360..453dc10af9 100644
--- a/chip/stm32/keyboard_scan.c
+++ b/chip/stm32/keyboard_scan.c
@@ -33,16 +33,14 @@ enum COL_INDEX {
 #define POLLING_MODE_TIMEOUT 100000   /* 100 ms */
 #define SCAN_LOOP_DELAY 10000         /*  10 ms */
 
-#define KB_COLS 13
-
 /* 15:14, 12:8, 2 */
 #define IRQ_MASK 0xdf04
 
 /* The keyboard state from the last read */
-static uint8_t raw_state[KB_COLS];
+static uint8_t raw_state[KB_OUTPUTS];
 
 /* The keyboard state we will return when requested */
-static uint8_t saved_state[KB_COLS];
+static uint8_t saved_state[KB_OUTPUTS];
 
 /* Mask with 1 bits only for keys that actually exist */
 static const uint8_t *actual_key_mask;
@@ -50,7 +48,7 @@ static const uint8_t *actual_key_mask;
 /* All actual key masks (todo: move to keyboard matrix definition) */
 /* TODO: (crosbug.com/p/7485) fill in real key mask with 0-bits for coords that
    aren't keys */
-static const uint8_t actual_key_masks[4][KB_COLS] = {
+static const uint8_t actual_key_masks[4][KB_OUTPUTS] = {
 	{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
 	 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
 	{0},
@@ -169,7 +167,7 @@ static int check_keys_changed(void)
 	int change = 0;
 	int num_press = 0;
 
-	for (c = 0; c < KB_COLS; c++) {
+	for (c = 0; c < KB_OUTPUTS; c++) {
 		uint16_t tmp;
 
 		/* Select column, then wait a bit for it to settle */
@@ -221,7 +219,7 @@ static int check_keys_changed(void)
 	select_column(COL_TRI_STATE_ALL);
 
 	/* Count number of key pressed */
-	for (c = 0; c < KB_COLS; c++) {
+	for (c = 0; c < KB_OUTPUTS; c++) {
 		if (raw_state[c])
 			++num_press;
 	}
@@ -231,7 +229,7 @@ static int check_keys_changed(void)
 		board_keyboard_scan_ready();
 
 		CPRINTF("[%d keys pressed: ", num_press);
-		for (c = 0; c < KB_COLS; c++) {
+		for (c = 0; c < KB_OUTPUTS; c++) {
 			if (raw_state[c])
 				CPRINTF(" %02x", raw_state[c]);
 			else