diff --git a/library/x509_crt.c b/library/x509_crt.c
index a3517f6..16a29b5 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1403,6 +1403,7 @@
     { BADCERT_KEY_USAGE,     "Usage does not match the keyUsage extension" },
     { BADCERT_EXT_KEY_USAGE, "Usage does not match the extendedKeyUsage extension" },
     { BADCERT_NS_CERT_TYPE,  "Usage does not match the nsCertType extension" },
+    { BADCERT_BAD_KEY,       "The certificate uses an invalid key (e.g. unsupported elliptic curve)" },
     { 0, NULL }
 };