diff --git a/boot/zephyr/include/mcuboot-mbedtls-cfg.h b/boot/zephyr/include/mcuboot-mbedtls-cfg.h
new file mode 100644
index 0000000..14cd9eb
--- /dev/null
+++ b/boot/zephyr/include/mcuboot-mbedtls-cfg.h
@@ -0,0 +1,32 @@
+/*
+ *  Copyright (C) 2018 Open Source Foundries Limited
+ *  SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _MCUBOOT_MBEDTLS_CONFIG_
+#define _MCUBOOT_MBEDTLS_CONFIG_
+
+/**
+ * @file
+ *
+ * This is the top-level mbedTLS configuration file for MCUboot. The
+ * configuration depends on the signature type, so this file just
+ * pulls in the right header depending on that setting.
+ */
+
+/*
+ * IMPORTANT:
+ *
+ * If you put any "generic" definitions in here, make sure to update
+ * the simulator build.rs accordingly.
+ */
+
+#ifdef CONFIG_BOOT_SIGNATURE_TYPE_RSA
+#include "config-rsa.h"
+#elif defined(CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256)
+#include "config-asn1.h"
+#else
+#error "Cannot configure mbedTLS; signature type is unknown."
+#endif
+
+#endif