diff --git a/sim/mcuboot-sys/build.rs b/sim/mcuboot-sys/build.rs
index acc2af2..dd92988 100644
--- a/sim/mcuboot-sys/build.rs
+++ b/sim/mcuboot-sys/build.rs
@@ -359,7 +359,7 @@
         conf.file("../../boot/bootutil/src/image_rsa.c");
     } else if sig_ecdsa || sig_ecdsa_mbedtls {
         conf.conf.include("../../ext/mbedtls/include");
-        conf.file("../../boot/bootutil/src/image_ec256.c");
+        conf.file("../../boot/bootutil/src/image_ecdsa.c");
     } else if sig_ed25519 {
         conf.file("../../boot/bootutil/src/image_ed25519.c");
     }