diff --git a/schema/cryptography-defs.json b/schema/cryptography-defs.json
index 2d1a7f19..b86b60fc 100644
--- a/schema/cryptography-defs.json
+++ b/schema/cryptography-defs.json
@@ -40,6 +40,16 @@
         }
       ]
     },
+    {
+      "family": "RSA-X931",
+      "standard": [],
+      "variant": [
+        {
+          "pattern": "RSA-X9.31[-{hashAlgorithm}][-{keyLength}]",
+          "primitive": "signature"
+        }
+      ]
+    },
     {
       "family": "RSAES-PKCS1",
       "standard": [