diff --git a/configs/baremetal_test.h b/configs/baremetal_test.h
index 33b5167..7a03777 100644
--- a/configs/baremetal_test.h
+++ b/configs/baremetal_test.h
@@ -43,6 +43,9 @@
 /* Use Mbed TLS' timer implementation for Linux. */
 #define MBEDTLS_TIMING_C
 
+/* Needed for certificates in ssl_opt.sh */
+#define MBEDTLS_FS_IO
+
 #undef MBEDTLS_NO_PLATFORM_ENTROPY
 
 #undef  MBEDTLS_ENTROPY_MAX_SOURCES