diff --git a/boot/zephyr/keys.c b/boot/zephyr/keys.c
index 56b78df..467a0a1 100644
--- a/boot/zephyr/keys.c
+++ b/boot/zephyr/keys.c
@@ -19,7 +19,17 @@
 
 #include <bootutil/sign_key.h>
 
+/*
+ * Even though this is in principle a Zephyr-specific file, the
+ * simulator builds it and uses it as well. Because of that, we can't
+ * use Kconfig symbols for key types, and have to rely on the MCUBoot
+ * symbols (which Zephyr provides via this header, and the simulator
+ * provides via the compiler command line).
+ */
+#include <mcuboot_config/mcuboot_config.h>
+
 #if defined(MCUBOOT_SIGN_RSA)
+#define HAVE_KEYS
 const unsigned char root_pub_der[] = {
     0x30, 0x82, 0x01, 0x0a, 0x02, 0x82, 0x01, 0x01, 0x00, 0xd1, 0x06, 0x08,
     0x1a, 0x18, 0x44, 0x2c, 0x18, 0xe8, 0xfb, 0xfd, 0xf7, 0x0d, 0xa3, 0x4f,
@@ -47,6 +57,7 @@
 };
 const unsigned int root_pub_der_len = 270;
 #elif defined(MCUBOOT_SIGN_EC256)
+#define HAVE_KEYS
 const unsigned char root_pub_der[] = {
     0x30, 0x59, 0x30, 0x13, 0x06, 0x07, 0x2a, 0x86,
     0x48, 0xce, 0x3d, 0x02, 0x01, 0x06, 0x08, 0x2a,
@@ -65,7 +76,7 @@
 #error "No public key available for given signing algorithm."
 #endif
 
-#if defined(MCUBOOT_SIGN_RSA) || defined(MCUBOOT_SIGN_EC256)
+#if defined(HAVE_KEYS)
 const struct bootutil_key bootutil_keys[] = {
     {
         .key = root_pub_der,