diff --git a/sim/mcuboot-sys/csupport/run.c b/sim/mcuboot-sys/csupport/run.c
index dd63d55..5697948 100644
--- a/sim/mcuboot-sys/csupport/run.c
+++ b/sim/mcuboot-sys/csupport/run.c
@@ -454,3 +454,8 @@
 {
     return BOOT_MAX_ALIGN;
 }
+
+uint32_t boot_magic_sz(void)
+{
+    return BOOT_MAGIC_SZ;
+}
diff --git a/sim/mcuboot-sys/src/c.rs b/sim/mcuboot-sys/src/c.rs
index 3d2f3ea..f3de302 100644
--- a/sim/mcuboot-sys/src/c.rs
+++ b/sim/mcuboot-sys/src/c.rs
@@ -41,7 +41,7 @@
 }
 
 pub fn boot_magic_sz() -> usize {
-    unsafe { raw::BOOT_MAGIC_SZ as usize }
+    unsafe { raw::boot_magic_sz() as usize }
 }
 
 pub fn boot_max_align() -> usize {
@@ -83,7 +83,7 @@
 
         pub fn boot_trailer_sz(min_write_sz: u8) -> u32;
 
-        pub static BOOT_MAGIC_SZ: u32;
+        pub fn boot_magic_sz() -> u32;
         pub fn boot_max_align() -> u32;
 
         pub fn rsa_oaep_encrypt_(pubkey: *const u8, pubkey_len: libc::c_uint,