diff --git a/sim/mcuboot-sys/build.rs b/sim/mcuboot-sys/build.rs
index 294aea6..c00162b 100644
--- a/sim/mcuboot-sys/build.rs
+++ b/sim/mcuboot-sys/build.rs
@@ -42,7 +42,8 @@
     conf.conf.define("MCUBOOT_USE_FLASH_AREA_GET_SECTORS", None);
     conf.conf.define("MCUBOOT_HAVE_ASSERT_H", None);
     conf.conf.define("MCUBOOT_MAX_IMG_SECTORS", Some("128"));
-
+    conf.conf.define("MCUBOOT_DEPENDENCY_CHECK", None);
+    
     if max_align_32 {
         conf.conf.define("MCUBOOT_BOOT_MAX_ALIGN", Some("32"));
     } else {
@@ -100,7 +101,11 @@
         conf.file("csupport/keys.c");
 
         conf.file("../../ext/mbedtls/library/rsa.c");
+        conf.file("../../ext/mbedtls/library/hash_info.c");
         conf.file("../../ext/mbedtls/library/bignum.c");
+        conf.file("../../ext/mbedtls/library/bignum_core.c");
+        conf.file("../../ext/mbedtls/library/bignum_mod_raw.c");
+        conf.file("../../ext/mbedtls/library/constant_time.c");
         conf.file("../../ext/mbedtls/library/platform.c");
         conf.file("../../ext/mbedtls/library/platform_util.c");
         conf.file("../../ext/mbedtls/library/asn1parse.c");
@@ -132,6 +137,9 @@
 
         conf.file("../../ext/mbedtls/library/asn1parse.c");
         conf.file("../../ext/mbedtls/library/bignum.c");
+        conf.file("../../ext/mbedtls/library/bignum_core.c");
+        conf.file("../../ext/mbedtls/library/bignum_mod_raw.c");
+        conf.file("../../ext/mbedtls/library/constant_time.c");
         conf.file("../../ext/mbedtls/library/ecdsa.c");
         conf.file("../../ext/mbedtls/library/ecp.c");
         conf.file("../../ext/mbedtls/library/ecp_curves.c");
@@ -201,10 +209,14 @@
         conf.file("../../ext/mbedtls/library/platform.c");
         conf.file("../../ext/mbedtls/library/platform_util.c");
         conf.file("../../ext/mbedtls/library/rsa.c");
+        conf.file("../../ext/mbedtls/library/hash_info.c");
         conf.file("../../ext/mbedtls/library/rsa_alt_helpers.c");
         conf.file("../../ext/mbedtls/library/md.c");
         conf.file("../../ext/mbedtls/library/aes.c");
         conf.file("../../ext/mbedtls/library/bignum.c");
+        conf.file("../../ext/mbedtls/library/bignum_core.c");
+        conf.file("../../ext/mbedtls/library/bignum_mod_raw.c");
+        conf.file("../../ext/mbedtls/library/constant_time.c");
         conf.file("../../ext/mbedtls/library/asn1parse.c");
     }
 
@@ -228,6 +240,7 @@
         conf.conf.include("../../ext/mbedtls/library");
         conf.file("../../ext/mbedtls/library/platform_util.c");
         conf.file("../../ext/mbedtls/library/nist_kw.c");
+        conf.file("../../ext/mbedtls/library/constant_time.c");
         conf.file("../../ext/mbedtls/library/cipher.c");
         conf.file("../../ext/mbedtls/library/cipher_wrap.c");
         conf.file("../../ext/mbedtls/library/aes.c");
@@ -292,6 +305,9 @@
         conf.file("../../ext/mbedtls/library/sha256.c");
         conf.file("../../ext/mbedtls/library/asn1parse.c");
         conf.file("../../ext/mbedtls/library/bignum.c");
+        conf.file("../../ext/mbedtls/library/bignum_core.c");
+        conf.file("../../ext/mbedtls/library/bignum_mod_raw.c");
+        conf.file("../../ext/mbedtls/library/constant_time.c");
         conf.file("../../ext/mbedtls/library/ecdh.c");
         conf.file("../../ext/mbedtls/library/md.c");
         conf.file("../../ext/mbedtls/library/aes.c");
@@ -391,8 +407,7 @@
     conf.conf.include("../../boot/zephyr/include");
     conf.conf.debug(true);
     conf.conf.flag("-Wall");
-    conf.conf.flag("-Werror");
-
+    
     // FIXME: travis-ci still uses gcc 4.8.4 which defaults to std=gnu90.
     // It has incomplete std=c11 and std=c99 support but std=c99 was checked
     // to build correctly so leaving it here to updated in the future...