diff --git a/boot/zephyr/CMakeLists.txt b/boot/zephyr/CMakeLists.txt
index 2f47766e3..abb0f9a2d 100644
--- a/boot/zephyr/CMakeLists.txt
+++ b/boot/zephyr/CMakeLists.txt
@@ -309,8 +309,13 @@ elseif(CONFIG_BOOT_SIGNATURE_TYPE_ED25519 OR CONFIG_BOOT_ENCRYPT_X25519)
       ${FIAT_DIR}/src/curve25519.c
     )
   else()
+    if(MBEDTLS_ASN1_DIR)
+      zephyr_library_sources(
+        ${MBEDTLS_ASN1_DIR}/src/asn1parse.c
+      )
+    endif()
+
     zephyr_library_sources(
-      ${MBEDTLS_ASN1_DIR}/src/asn1parse.c
       ${BOOT_DIR}/bootutil/src/ed25519_psa.c
     )
   endif()
diff --git a/boot/zephyr/io_bm.c b/boot/zephyr/io_bm.c
index 3f65a5d0e..798cf7a3f 100644
--- a/boot/zephyr/io_bm.c
+++ b/boot/zephyr/io_bm.c
@@ -89,31 +89,13 @@ void io_led_set(int value)
 
 bool io_detect_pin(void)
 {
-    int rc;
     bool pin_active;
 
-    rc = bm_buttons_init(
-            &(struct bm_buttons_config){
-                .pin_number = BOARD_PIN_BTN_0,
-                .active_state = BM_BUTTONS_ACTIVE_LOW,
-                .pull_config = BM_BUTTONS_PIN_PULLUP,
-            },
-            1,
-            BM_BUTTONS_DETECTION_DELAY_MIN_US);
-    if (rc) {
-        BOOT_LOG_ERR("Failed to initialize buttons: %d", rc);
-        return false;
-    }
+    nrf_gpio_cfg_input(BOARD_PIN_BTN_0, BM_BUTTONS_PIN_PULLUP);
 
-    rc = bm_buttons_enable();
-    if (rc) {
-        BOOT_LOG_ERR("Failed to enable button detection: %d", rc);
-        return false;
-    }
+    pin_active = (bool)nrf_gpio_pin_read(BOARD_PIN_BTN_0);
 
-    pin_active = bm_buttons_is_pressed(BOARD_PIN_BTN_0);
-
-    if (pin_active) {
+    if (!pin_active) {
         if (BUTTON_0_DETECT_DELAY > 0) {
 #ifdef CONFIG_MULTITHREADING
             k_sleep(K_MSEC(50));
@@ -125,13 +107,15 @@ bool io_detect_pin(void)
             int64_t timestamp = k_uptime_get();
 
             for(;;) {
-                pin_active = bm_buttons_is_pressed(BOARD_PIN_BTN_0);
+                uint32_t delta;
+
+                pin_active = (bool)nrf_gpio_pin_read(BOARD_PIN_BTN_0);
 
                 /* Get delta from when this started */
-                uint32_t delta = k_uptime_get() -  timestamp;
+                delta = k_uptime_get() -  timestamp;
 
                 /* If not pressed OR if pressed > debounce period, stop. */
-                if (delta >= BUTTON_0_DETECT_DELAY || !pin_active) {
+                if (delta >= BUTTON_0_DETECT_DELAY || pin_active) {
                     break;
                 }
 
@@ -145,18 +129,7 @@ bool io_detect_pin(void)
         }
     }
 
-    rc = bm_buttons_disable();
-
-    if (rc) {
-        BOOT_LOG_ERR("Failed to disable buttons: %d", rc);
-    }
-
-    rc = bm_buttons_deinit();
-    if (rc) {
-        BOOT_LOG_ERR("Failed to de-initialize buttons: %d", rc);
-    }
-
-    return (bool)pin_active;
+    return (bool)!pin_active;
 }
 #endif