diff --git a/library/x509_crt.c b/library/x509_crt.c
index d4e0ffd..fdddbd3 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -157,6 +157,17 @@
 };
 
 /*
+ * Empty / all-forbidden profile
+ */
+const mbedtls_x509_crt_profile mbedtls_x509_crt_profile_none =
+{
+    0,
+    0,
+    0,
+    (uint32_t) -1,
+};
+
+/*
  * Check md_alg against profile
  * Return 0 if md_alg is acceptable for this profile, -1 otherwise
  */