diff --git a/scripts/imgtool/image.py b/scripts/imgtool/image.py
index 5114bf4..5fba119 100644
--- a/scripts/imgtool/image.py
+++ b/scripts/imgtool/image.py
@@ -172,13 +172,13 @@
                 0x35, 0x52, 0x50, 0x0f,
                 0x2c, 0xb6, 0x79, 0x80, ])
         else:
-            align_lsb = self.max_align & 0x00ff
-            align_msb = (self.max_align & 0xff00) >> 8
-            self.boot_magic = bytes([
-                align_lsb, align_msb, 0x2d, 0xe1,
-                0x5d, 0x29, 0x41, 0x0b,
-                0x8d, 0x77, 0x67, 0x9c,
-                0x11, 0x0f, 0x1f, 0x8a, ])
+            lsb = self.max_align & 0x00ff
+            msb = (self.max_align & 0xff00) >> 8
+            align = bytes([msb, lsb]) if self.endian == "big" else bytes([lsb, msb])
+            self.boot_magic = align + bytes([0x2d, 0xe1,
+                                            0x5d, 0x29, 0x41, 0x0b,
+                                            0x8d, 0x77, 0x67, 0x9c,
+                                            0x11, 0x0f, 0x1f, 0x8a, ])
 
         if security_counter == 'auto':
             # Security counter has not been explicitly provided,