diff --git a/src/sonic-yang-models/tests/yang_model_tests/tests_config/macsec.json b/src/sonic-yang-models/tests/yang_model_tests/tests_config/macsec.json
index 5c748606ee..89abcb3866 100644
--- a/src/sonic-yang-models/tests/yang_model_tests/tests_config/macsec.json
+++ b/src/sonic-yang-models/tests/yang_model_tests/tests_config/macsec.json
@@ -30,6 +30,18 @@
                         "replay_window": 64,
                         "send_sci": "true",
                         "rekey_period": 3600
+                    },
+                    {
+                        "name": "test_nofallback",
+                        "priority": 64,
+                        "cipher_suite": "GCM-AES-XPN-256",
+                        "primary_cak": "5207554155500e5d5157786d6c2a3d2031425a5e577e7e727f6b6c03312432262706080a00005b554f4e007975707670725b0a54540c0252445e5d7a29252b046a",
+                        "primary_ckn": "6162636465666768696A6B6C6D6E6F706162636465666768696A6B6C6D6E6F70",
+                        "policy": "security",
+                        "enable_replay_protect": "true",
+                        "replay_window": 64,
+                        "send_sci": "true",
+                        "rekey_period": 3600
                     }
                 ]
             }
diff --git a/src/sonic-yang-models/yang-models/sonic-macsec.yang b/src/sonic-yang-models/yang-models/sonic-macsec.yang
index b3d04b725a..2d76737ee4 100644
--- a/src/sonic-yang-models/yang-models/sonic-macsec.yang
+++ b/src/sonic-yang-models/yang-models/sonic-macsec.yang
@@ -70,9 +70,9 @@ module sonic-macsec {
                     }
                 }
 
-                must "string-length(fallback_cak) = string-length(primary_cak)";
+                must "string-length(fallback_cak) = 0 or string-length(fallback_cak) = string-length(primary_cak)";
 
-                must "primary_ckn != fallback_ckn";
+                must "string-length(fallback_ckn) = 0 or primary_ckn != fallback_ckn";
 
                 leaf policy {
                     type string {