diff --git a/sim/mcuboot-sys/build.rs b/sim/mcuboot-sys/build.rs
index 5f5eeac..ebff3c5 100644
--- a/sim/mcuboot-sys/build.rs
+++ b/sim/mcuboot-sys/build.rs
@@ -81,6 +81,7 @@
     conf.file("csupport/run.c");
     conf.include("../../boot/bootutil/include");
     conf.include("../../boot/zephyr/include");
+    conf.include("csupport");
     conf.debug(true);
     conf.flag("-Wall");
     conf.flag("-Werror");
diff --git a/sim/mcuboot-sys/csupport/bootsim.h b/sim/mcuboot-sys/csupport/bootsim.h
new file mode 100644
index 0000000..f3fc5e4
--- /dev/null
+++ b/sim/mcuboot-sys/csupport/bootsim.h
@@ -0,0 +1,7 @@
+#ifndef H_BOOTSIM_
+#define H_BOOTSIM_
+
+void sim_assert(int, const char *test, const char *, unsigned int, const char *);
+#define ASSERT(x) sim_assert((x), #x, __FILE__, __LINE__, __func__)
+
+#endif
diff --git a/sim/mcuboot-sys/csupport/run.c b/sim/mcuboot-sys/csupport/run.c
index 91d779a..9b5e36e 100644
--- a/sim/mcuboot-sys/csupport/run.c
+++ b/sim/mcuboot-sys/csupport/run.c
@@ -10,6 +10,7 @@
 #include "flash_map/flash_map.h"
 
 #include "../../../boot/bootutil/src/bootutil_priv.h"
+#include "bootsim.h"
 
 #ifdef MCUBOOT_SIGN_EC256
 #include "../../../ext/tinycrypt/lib/include/tinycrypt/ecc_dsa.h"