diff --git a/certs/test/catalog.txt b/certs/test/catalog.txt
new file mode 100644
index 000000000..dcc1393d4
--- /dev/null
+++ b/certs/test/catalog.txt
@@ -0,0 +1,3 @@
+crit-cert.pem:
+  Simple self-signed certificate with critical Basic Constraints and Key Usage
+  extensions.
diff --git a/certs/test/crit-cert.pem b/certs/test/crit-cert.pem
new file mode 100644
index 000000000..e2c370f54
--- /dev/null
+++ b/certs/test/crit-cert.pem
@@ -0,0 +1,18 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/certs/test/crit-key.pem b/certs/test/crit-key.pem
new file mode 100644
index 000000000..893f07eb1
--- /dev/null
+++ b/certs/test/crit-key.pem
@@ -0,0 +1,9 @@
+-----BEGIN RSA PRIVATE KEY-----
+MIIBOQIBAAJBAOJwQE7W77KzLuJqRYB7Aoxg8rDNjo5qr4VSimtIiOCtfwkhXmCe
+e9PQetX8m7a3iwHLjWtlznRyo506P3Jly1ECAwEAAQJAG21BPMtn6Rsu+JmqpW9A
+1cQAYU3kkHd3nwxqW6hDfAMNY8qZCkGsrBxSAgvIItQwytV7zn+F8FPDwViVz1xQ
+gQIhAPWkmZGz7sRIuZB4JQiXzVJvUprsfgpg6ODfpWl+cabJAiEA6/xdEuMqbiY+
+g7xG1MMOe2zstDB+vvxT5pEQxGklXEkCIBo9qC4Zc6NCRZh6TTJ6zPNGcyObqec/
+7QDAw3HekROJAiBm+N7QIAniuJNsvloV+us11kjPM54KzmX55PDxE4R26QIgU5DH
+iIm5DKbAJqgaXOXo35v/PUqYZmJUc2bPF158+vg=
+-----END RSA PRIVATE KEY-----
diff --git a/ctaocrypt/src/error.c b/ctaocrypt/src/error.c
index d7ed45194..67b49e42d 100644
--- a/ctaocrypt/src/error.c
+++ b/ctaocrypt/src/error.c
@@ -243,6 +243,10 @@ void CTaoCryptErrorString(int error, char* buffer)
         XSTRNCPY(buffer, "ASN NTRU key decode error, invalid input", max);
         break;
 
+    case ASN_CRIT_EXT_E:
+        XSTRNCPY(buffer, "X.509 Critical extension ignored", max);
+        break;
+
     case ECC_BAD_ARG_E :
         XSTRNCPY(buffer, "ECC input argument wrong type, invalid input", max);
         break;