diff --git a/sim/mcuboot-sys/csupport/run.c b/sim/mcuboot-sys/csupport/run.c
index f531db9..a0e4448 100644
--- a/sim/mcuboot-sys/csupport/run.c
+++ b/sim/mcuboot-sys/csupport/run.c
@@ -42,7 +42,7 @@
         uint32_t size);
 extern int sim_flash_write(uint8_t flash_id, uint32_t offset, const uint8_t *src,
         uint32_t size);
-extern uint8_t sim_flash_align(uint8_t flash_id);
+extern uint16_t sim_flash_align(uint8_t flash_id);
 extern uint8_t sim_flash_erased_val(uint8_t flash_id);
 
 struct sim_context {
@@ -202,7 +202,7 @@
 #endif
 }
 
-uint8_t flash_area_align(const struct flash_area *area)
+uint16_t flash_area_align(const struct flash_area *area)
 {
     return sim_flash_align(area->fa_device_id);
 }
diff --git a/sim/mcuboot-sys/csupport/storage/flash_map.h b/sim/mcuboot-sys/csupport/storage/flash_map.h
index b27a90c..5d420f7 100644
--- a/sim/mcuboot-sys/csupport/storage/flash_map.h
+++ b/sim/mcuboot-sys/csupport/storage/flash_map.h
@@ -123,7 +123,7 @@
 /*
  * Alignment restriction for flash writes.
  */
-uint8_t flash_area_align(const struct flash_area *);
+uint16_t flash_area_align(const struct flash_area *);
 
 /*
  * What is value is read from erased flash bytes.
diff --git a/sim/mcuboot-sys/src/api.rs b/sim/mcuboot-sys/src/api.rs
index a88cfcf..8b180cf 100644
--- a/sim/mcuboot-sys/src/api.rs
+++ b/sim/mcuboot-sys/src/api.rs
@@ -21,7 +21,7 @@
 pub type FlashMap = HashMap<u8, FlashPtr>;
 
 pub struct FlashParamsStruct {
-    align: u8,
+    align: u16,
     erased_val: u8,
 }
 
@@ -81,7 +81,7 @@
 pub unsafe fn set_flash(dev_id: u8, dev: &mut dyn Flash) {
     THREAD_CTX.with(|ctx| {
         ctx.borrow_mut().flash_params.insert(dev_id, FlashParamsStruct {
-            align: dev.align() as u8,
+            align: dev.align() as u16,
             erased_val: dev.erased_val(),
         });
         let dev: &'static mut dyn Flash = mem::transmute(dev);
@@ -179,7 +179,7 @@
 }
 
 #[no_mangle]
-pub extern fn sim_flash_align(id: u8) -> u8 {
+pub extern fn sim_flash_align(id: u8) -> u16 {
     THREAD_CTX.with(|ctx| {
         ctx.borrow().flash_params.get(&id).unwrap().align
     })