diff --git a/boot/zephyr/flash_map_extended.c b/boot/zephyr/flash_map_extended.c
index 4f6749b..aa472c5 100644
--- a/boot/zephyr/flash_map_extended.c
+++ b/boot/zephyr/flash_map_extended.c
@@ -69,8 +69,30 @@
     return rc;
 }
 
+#define ERASED_VAL 0xff
 uint8_t flash_area_erased_val(const struct flash_area *fap)
 {
     (void)fap;
-    return 0xff;
+    return ERASED_VAL;
+}
+
+int flash_area_read_is_empty(const struct flash_area *fa, uint32_t off,
+        void *dst, uint32_t len)
+{
+    uint8_t i;
+    uint8_t *u8dst;
+    int rc;
+
+    rc = hal_flash_read(fa->fa_device_id, fa->fa_off + off, dst, len);
+    if (rc) {
+        return -1;
+    }
+
+    for (i = 0, u8dst = (uint8_t *)dst; i < len; i++) {
+        if (u8dst[i] != ERASED_VAL) {
+            return 0;
+        }
+    }
+
+    return 1;
 }
diff --git a/boot/zephyr/include/flash_map_backend/flash_map_backend.h b/boot/zephyr/include/flash_map_backend/flash_map_backend.h
index ae347cf..178c34f 100644
--- a/boot/zephyr/include/flash_map_backend/flash_map_backend.h
+++ b/boot/zephyr/include/flash_map_backend/flash_map_backend.h
@@ -64,6 +64,14 @@
  */
 uint8_t flash_area_erased_val(const struct flash_area *fap);
 
+/*
+ * Reads len bytes from off, and checks if the read data is erased.
+ *
+ * Returns 1 if erased, 0 if non-erased, and -1 on failure.
+ */
+int flash_area_read_is_empty(const struct flash_area *fa, uint32_t off,
+        void *dst, uint32_t len);
+
 #ifdef __cplusplus
 }
 #endif