diff --git a/drivers/display/Kconfig.microbit b/drivers/display/Kconfig.microbit
index a4d4a9d237d..6e188874dad 100644
--- a/drivers/display/Kconfig.microbit
+++ b/drivers/display/Kconfig.microbit
@@ -8,7 +8,6 @@ config MICROBIT_DISPLAY
 	depends on BOARD_BBC_MICROBIT
 	depends on PRINTK
 	depends on GPIO
-	select LEGACY_TIMEOUT_API
 	help
 	  Enable this to be able to display images and text on the 5x5
 	  LED matrix display on the BBC micro:bit.
diff --git a/drivers/display/mb_display.c b/drivers/display/mb_display.c
index d5c4ded8a5a..1247b406ac5 100644
--- a/drivers/display/mb_display.c
+++ b/drivers/display/mb_display.c
@@ -79,7 +79,7 @@
 #define SCROLL_OFF   0
 #define SCROLL_START 1
 
-#define SCROLL_DEFAULT_DURATION K_MSEC(80)
+#define SCROLL_DEFAULT_DURATION_MS 80
 
 struct mb_display {
 	struct device  *dev;         /* GPIO device */
@@ -160,8 +160,8 @@ static void start_image(struct mb_display *disp, const struct mb_image *img)
 
 	disp->cur = 0U;
 
-	if (disp->duration == K_FOREVER) {
-		disp->expiry = K_FOREVER;
+	if (disp->duration == SYS_FOREVER_MS) {
+		disp->expiry = SYS_FOREVER_MS;
 	} else {
 		disp->expiry = k_uptime_get() + disp->duration;
 	}
@@ -308,7 +308,7 @@ static void show_row(struct k_timer *timer)
 	update_pins(disp, disp->row[disp->cur]);
 	disp->cur = (disp->cur + 1) % DISPLAY_ROWS;
 
-	if (disp->cur == 0U && disp->expiry != K_FOREVER &&
+	if (disp->cur == 0U && disp->expiry != SYS_FOREVER_MS &&
 	    k_uptime_get() > disp->expiry) {
 		if (disp->scroll) {
 			update_scroll(disp);
@@ -335,7 +335,7 @@ static void start_scroll(struct mb_display *disp, s32_t duration)
 	if (duration) {
 		disp->duration = duration / scroll_steps(disp);
 	} else {
-		disp->duration = SCROLL_DEFAULT_DURATION;
+		disp->duration = SCROLL_DEFAULT_DURATION_MS;
 	}
 
 	disp->scroll = SCROLL_START;
diff --git a/include/display/mb_display.h b/include/display/mb_display.h
index f38bb424283..0ad091a45c0 100644
--- a/include/display/mb_display.h
+++ b/include/display/mb_display.h
@@ -124,7 +124,8 @@ struct mb_display *mb_display_get(void);
  *
  * @param disp      Display object.
  * @param mode      One of the MB_DISPLAY_MODE_* options.
- * @param duration  Duration how long to show each image (in milliseconds).
+ * @param duration  Duration how long to show each image (in milliseconds), or
+ *                  @ref SYS_FOREVER_MS.
  * @param img       Array of image bitmaps (struct mb_image objects).
  * @param img_count Number of images in 'img' array.
  */
@@ -143,7 +144,8 @@ void mb_display_image(struct mb_display *disp, u32_t mode, s32_t duration,
  *
  * @param disp     Display object.
  * @param mode     One of the MB_DISPLAY_MODE_* options.
- * @param duration Duration how long to show each character (in milliseconds).
+ * @param duration Duration how long to show each character (in milliseconds),
+ *                 or @ref SYS_FOREVER_MS.
  * @param fmt      printf-style format string
  * @param ...      Optional list of format arguments.
  */
diff --git a/samples/bluetooth/mesh/src/microbit.c b/samples/bluetooth/mesh/src/microbit.c
index 5ee14c7efff..bf086c8581a 100644
--- a/samples/bluetooth/mesh/src/microbit.c
+++ b/samples/bluetooth/mesh/src/microbit.c
@@ -22,8 +22,8 @@ static void button_pressed(struct device *dev, struct gpio_callback *cb,
 {
 	struct mb_display *disp = mb_display_get();
 
-	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, K_MSEC(500),
-			 "%04u", oob_number);
+	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, 500, "%04u",
+			 oob_number);
 }
 
 static void configure_button(void)
@@ -57,7 +57,8 @@ void board_output_number(bt_mesh_output_action_t action, u32_t number)
 	gpio_pin_interrupt_configure(gpio, DT_GPIO_PIN(DT_ALIAS(sw0), gpios),
 				     GPIO_INT_EDGE_TO_ACTIVE);
 
-	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, K_FOREVER, &arrow, 1);
+	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, SYS_FOREVER_MS, &arrow,
+			 1);
 }
 
 void board_prov_complete(void)
@@ -73,7 +74,7 @@ void board_prov_complete(void)
 	gpio_pin_interrupt_configure(gpio, DT_GPIO_PIN(DT_ALIAS(sw0), gpios),
 				     GPIO_INT_DISABLE);
 
-	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, K_SECONDS(10),
+	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, 10 * MSEC_PER_SEC,
 			 &arrow, 1);
 }
 
@@ -94,7 +95,7 @@ void board_init(void)
 	};
 
 	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT | MB_DISPLAY_FLAG_LOOP,
-			 K_SECONDS(1), blink, ARRAY_SIZE(blink));
+			 1 * MSEC_PER_SEC, blink, ARRAY_SIZE(blink));
 
 	configure_button();
 }
diff --git a/samples/bluetooth/mesh_demo/src/microbit.c b/samples/bluetooth/mesh_demo/src/microbit.c
index 61e705420b4..a9f6641d9a0 100644
--- a/samples/bluetooth/mesh_demo/src/microbit.c
+++ b/samples/bluetooth/mesh_demo/src/microbit.c
@@ -20,7 +20,7 @@
 
 #include "board.h"
 
-#define SCROLL_SPEED   K_MSEC(300)
+#define SCROLL_SPEED   300
 
 #define BUZZER_PIN     EXT_P0_GPIO_PIN
 #define BEEP_DURATION  K_MSEC(60)
@@ -53,10 +53,10 @@ static void button_pressed(struct device *dev, struct gpio_callback *cb,
 
 		if (target > 0x0009) {
 			mb_display_print(disp, MB_DISPLAY_MODE_SINGLE,
-					 K_SECONDS(2), "A");
+					 2 * MSEC_PER_SEC, "A");
 		} else {
 			mb_display_print(disp, MB_DISPLAY_MODE_SINGLE,
-					 K_SECONDS(2), "%X", (target & 0xf));
+					 2 * MSEC_PER_SEC, "%X", (target & 0xf));
 		}
 	}
 }
@@ -172,7 +172,7 @@ void board_heartbeat(u8_t hops, u16_t feat)
 
 	if (hops) {
 		hops = MIN(hops, ARRAY_SIZE(hops_img));
-		mb_display_image(disp, MB_DISPLAY_MODE_SINGLE, K_SECONDS(2),
+		mb_display_image(disp, MB_DISPLAY_MODE_SINGLE, 2 * MSEC_PER_SEC,
 				 &hops_img[hops - 1], 1);
 	}
 }
@@ -183,8 +183,8 @@ void board_other_dev_pressed(u16_t addr)
 
 	printk("board_other_dev_pressed(0x%04x)\n", addr);
 
-	mb_display_print(disp, MB_DISPLAY_MODE_SINGLE, K_SECONDS(2),
-			 "%X", (addr & 0xf));
+	mb_display_print(disp, MB_DISPLAY_MODE_SINGLE, 2 * MSEC_PER_SEC, "%X",
+			 (addr & 0xf));
 }
 
 void board_attention(bool attention)
@@ -216,7 +216,7 @@ void board_attention(bool attention)
 	if (attention) {
 		mb_display_image(disp,
 				 MB_DISPLAY_MODE_DEFAULT | MB_DISPLAY_FLAG_LOOP,
-				 K_MSEC(150), attn_img, ARRAY_SIZE(attn_img));
+				 150, attn_img, ARRAY_SIZE(attn_img));
 	} else {
 		mb_display_stop(disp);
 	}
diff --git a/samples/boards/bbc_microbit/display/src/main.c b/samples/boards/bbc_microbit/display/src/main.c
index 2258e8f450d..c0784cb81ca 100644
--- a/samples/boards/bbc_microbit/display/src/main.c
+++ b/samples/boards/bbc_microbit/display/src/main.c
@@ -72,7 +72,7 @@ void main(void)
 
 	/* Display countdown from '9' to '0' */
 	mb_display_print(disp, MB_DISPLAY_MODE_SINGLE,
-			 K_SECONDS(1), "9876543210");
+			 1 * MSEC_PER_SEC, "9876543210");
 	k_sleep(K_SECONDS(11));
 
 	/* Iterate through all pixels one-by-one */
@@ -80,28 +80,28 @@ void main(void)
 		for (x = 0; x < 5; x++) {
 			struct mb_image pixel = {};
 			pixel.row[y] = BIT(x);
-			mb_display_image(disp, MB_DISPLAY_MODE_SINGLE,
-					 K_MSEC(250), &pixel, 1);
+			mb_display_image(disp, MB_DISPLAY_MODE_SINGLE, 250,
+					 &pixel, 1);
 			k_sleep(K_MSEC(300));
 		}
 	}
 
 	/* Show a smiley-face */
-	mb_display_image(disp, MB_DISPLAY_MODE_SINGLE, K_SECONDS(2),
+	mb_display_image(disp, MB_DISPLAY_MODE_SINGLE, 2 * MSEC_PER_SEC,
 			 &smiley, 1);
 	k_sleep(K_SECONDS(2));
 
 	/* Show a short scrolling animation */
-	mb_display_image(disp, MB_DISPLAY_MODE_SCROLL, K_SECONDS(1),
+	mb_display_image(disp, MB_DISPLAY_MODE_SCROLL, 1 * MSEC_PER_SEC,
 			 scroll, ARRAY_SIZE(scroll));
-	k_sleep(K_SECONDS(1) * (ARRAY_SIZE(scroll) + 2));
+	k_sleep(K_SECONDS((ARRAY_SIZE(scroll) + 2)));
 
 	/* Show a sequential animation */
 	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT | MB_DISPLAY_FLAG_LOOP,
-			 K_MSEC(150), animation, ARRAY_SIZE(animation));
-	k_sleep(K_MSEC(150) * ARRAY_SIZE(animation) * 5);
+			 150, animation, ARRAY_SIZE(animation));
+	k_sleep(K_MSEC(150 * ARRAY_SIZE(animation) * 5));
 
 	/* Show some scrolling text ("Hello Zephyr!") */
 	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT | MB_DISPLAY_FLAG_LOOP,
-			 K_MSEC(500), "Hello Zephyr!");
+			 500, "Hello Zephyr!");
 }
diff --git a/samples/boards/bbc_microbit/pong/src/ble.c b/samples/boards/bbc_microbit/pong/src/ble.c
index 86985899a74..489dfd75785 100644
--- a/samples/boards/bbc_microbit/pong/src/ble.c
+++ b/samples/boards/bbc_microbit/pong/src/ble.c
@@ -395,12 +395,12 @@ static u32_t adv_timeout(void)
 	u32_t timeout;
 
 	if (bt_rand(&timeout, sizeof(timeout)) < 0) {
-		return K_SECONDS(10);
+		return 10 * MSEC_PER_SEC;
 	}
 
-	timeout %= K_SECONDS(10);
+	timeout %= (10 * MSEC_PER_SEC);
 
-	return timeout + K_SECONDS(1);
+	return timeout + (1 * MSEC_PER_SEC);
 }
 
 static void cancel_connect(void)
@@ -474,7 +474,7 @@ static void ble_timeout(struct k_work *work)
 
 		printk("Advertising successfully started\n");
 		ble_state = BLE_ADVERTISING;
-		k_delayed_work_submit(&ble_work, adv_timeout());
+		k_delayed_work_submit(&ble_work, K_MSEC(adv_timeout()));
 		break;
 	case BLE_ADVERTISING:
 		printk("Timed out advertising\n");
diff --git a/samples/boards/bbc_microbit/pong/src/main.c b/samples/boards/bbc_microbit/pong/src/main.c
index eac562b2ef3..75ac364e059 100644
--- a/samples/boards/bbc_microbit/pong/src/main.c
+++ b/samples/boards/bbc_microbit/pong/src/main.c
@@ -25,7 +25,7 @@
  * system where top-left is (0, 0) and bottom-right is (49, 49).
  */
 
-#define SCROLL_SPEED      K_MSEC(400)  /* Text scrolling speed */
+#define SCROLL_SPEED      400          /* Text scrolling speed */
 
 #define PIXEL_SIZE        10           /* Virtual coordinates per real pixel */
 
@@ -42,8 +42,10 @@
 #define BALL_POS_Y_MIN    0            /* Maximum ball Y coordinate */
 #define BALL_POS_Y_MAX    39           /* Maximum ball Y coordinate */
 
-#define START_THRESHOLD   K_MSEC(100)  /* Max time between A & B press */
-#define RESTART_THRESHOLD K_SECONDS(2) /* Time before restart is allowed */
+#define START_THRESHOLD   100          /* Max time between A & B press */
+#define RESTART_THRESHOLD (2 * MSEC_PER_SEC) /* Time before restart is
+					      *	allowed
+					      */
 
 #define REAL_TO_VIRT(r)  ((r) * 10)
 #define VIRT_TO_REAL(v)  ((v) / 10)
@@ -295,7 +297,7 @@ static void game_ended(bool won)
 		printk("You lost!\n");
 	}
 
-	k_delayed_work_submit(&refresh, RESTART_THRESHOLD);
+	k_delayed_work_submit(&refresh, K_MSEC(RESTART_THRESHOLD));
 }
 
 static void game_stack_dump(const struct k_thread *thread, void *user_data)
@@ -396,13 +398,13 @@ static void button_pressed(struct device *dev, struct gpio_callback *cb,
 	/* Filter out spurious presses */
 	if (pins & BIT(DT_GPIO_PIN(DT_ALIAS(sw0), gpios))) {
 		printk("A pressed\n");
-		if (k_uptime_delta(&a_timestamp) < K_MSEC(100)) {
+		if (k_uptime_delta(&a_timestamp) < 100) {
 			printk("Too quick A presses\n");
 			return;
 		}
 	} else {
 		printk("B pressed\n");
-		if (k_uptime_delta(&b_timestamp) < K_MSEC(100)) {
+		if (k_uptime_delta(&b_timestamp) < 100) {
 			printk("Too quick B presses\n");
 			return;
 		}
@@ -538,6 +540,6 @@ void main(void)
 		}
 
 		mb_display_image(disp, MB_DISPLAY_MODE_SINGLE,
-				 K_FOREVER, &img, 1);
+				 SYS_FOREVER_MS, &img, 1);
 	}
 }
diff --git a/samples/boards/bbc_microbit/sound/src/main.c b/samples/boards/bbc_microbit/sound/src/main.c
index 110a5808262..9cb7919230a 100644
--- a/samples/boards/bbc_microbit/sound/src/main.c
+++ b/samples/boards/bbc_microbit/sound/src/main.c
@@ -72,7 +72,7 @@ static void button_pressed(struct device *dev, struct gpio_callback *cb,
 	printk("Period is %u us (%u Hz)\n", period, US_TO_HZ(period));
 
 	disp = mb_display_get();
-	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, K_MSEC(500), "%uHz",
+	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, 500, "%uHz",
 			 US_TO_HZ(period));
 
 	k_work_submit(&beep_work);
diff --git a/tests/bluetooth/mesh/src/microbit.c b/tests/bluetooth/mesh/src/microbit.c
index 8bbc98383be..f34bd37a6c3 100644
--- a/tests/bluetooth/mesh/src/microbit.c
+++ b/tests/bluetooth/mesh/src/microbit.c
@@ -22,7 +22,7 @@ static void button_pressed(struct device *dev, struct gpio_callback *cb,
 {
 	struct mb_display *disp = mb_display_get();
 
-	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, K_MSEC(500),
+	mb_display_print(disp, MB_DISPLAY_MODE_DEFAULT, 500,
 			 "OOB Number: %u", oob_number);
 }
 
@@ -58,7 +58,8 @@ void board_output_number(bt_mesh_output_action_t action, u32_t number)
 	gpio_pin_interrupt_configure(gpio, DT_GPIO_PIN(DT_ALIAS(sw0), gpios),
 				     GPIO_INT_EDGE_TO_ACTIVE);
 
-	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, K_FOREVER, &arrow, 1);
+	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, SYS_FOREVER_MS, &arrow,
+			 1);
 }
 
 void board_prov_complete(void)
@@ -74,7 +75,7 @@ void board_prov_complete(void)
 	gpio_pin_interrupt_configure(gpio, DT_GPIO_PIN(DT_ALIAS(sw0), gpios),
 				     GPIO_INT_DISABLE);
 
-	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, K_SECONDS(10),
+	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT, 10 * MSEC_PER_SEC,
 			 &arrow, 1);
 }
 
@@ -95,7 +96,7 @@ void board_init(void)
 	};
 
 	mb_display_image(disp, MB_DISPLAY_MODE_DEFAULT | MB_DISPLAY_FLAG_LOOP,
-			 K_SECONDS(1), blink, ARRAY_SIZE(blink));
+			 1 * MSEC_PER_SEC, blink, ARRAY_SIZE(blink));
 
 	configure_button();
 }