diff --git a/common/tests/fixtures/cardano/sign_tx_stake_pool_registration.json b/common/tests/fixtures/cardano/sign_tx_stake_pool_registration.json
index 71f319cd12..a1b4271b52 100644
--- a/common/tests/fixtures/cardano/sign_tx_stake_pool_registration.json
+++ b/common/tests/fixtures/cardano/sign_tx_stake_pool_registration.json
@@ -88,6 +88,90 @@
         "serialized_tx": "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"
       }
     },
+    {
+      "description": "Sample stake pool registration with zero margin",
+      "parameters": {
+        "protocol_magic": 764824073,
+        "network_id": 1,
+        "fee": 42,
+        "ttl": 10,
+        "certificates": [
+          {
+            "type": 3,
+            "pool_parameters": {
+              "pool_id": "f61c42cbf7c8c53af3f520508212ad3e72f674f957fe23ff0acb4973",
+              "vrf_key_hash": "198890ad6c92e80fbdab554dda02da9fb49d001bbd96181f3e07f7a6ab0d0640",
+              "pledge": 500000000,
+              "cost": 340000000,
+              "margin": {
+                "numerator": 0,
+                "denominator": 1
+              },
+              "reward_account": "stake1uya87zwnmax0v6nnn8ptqkl6ydx4522kpsc3l3wmf3yswygwx45el",
+              "owners": [
+                {
+                  "staking_key_path": "m/1852'/1815'/0'/2/0"
+                },
+                {
+                  "staking_key_hash": "3a7f09d3df4cf66a7399c2b05bfa234d5a29560c311fc5db4c490711"
+                }
+              ],
+              "relays": [
+                {
+                  "type": 0,
+                  "ipv4_address": "192.168.0.1",
+                  "ipv6_address": "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+                  "port": 1234
+                },
+                {
+                  "type": 0,
+                  "ipv6_address": "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+                  "port": 1234
+                },
+                {
+                  "type": 0,
+                  "ipv4_address": "192.168.0.1",
+                  "port": 1234
+                },
+                {
+                  "type": 1,
+                  "host_name": "www.test.test",
+                  "port": 1234
+                },
+                {
+                  "type": 2,
+                  "host_name": "www.test2.test"
+                }
+              ],
+              "metadata": {
+                "url": "https://www.test.test",
+                "hash": "914c57c1f12bbf4a82b12d977d4f274674856a11ed4b9b95bd70f5d41c5064a6"
+              }
+            }
+          }
+        ],
+        "withdrawals": [],
+        "metadata": "",
+        "input_flow": [["SWIPE", "SWIPE", "YES"], ["SWIPE", "YES"], ["SWIPE", "YES"], ["YES"], ["YES"]],
+        "inputs": [
+          {
+            "path": null,
+            "prev_hash": "3b40265111d8bb3c3c608d95b3a0bf83461ace32d79336579a1939b3aad1c0b7",
+            "prev_index": 0
+          }
+        ],
+        "outputs": [
+          {
+            "address": "addr1q84sh2j72ux0l03fxndjnhctdg7hcppsaejafsa84vh7lwgmcs5wgus8qt4atk45lvt4xfxpjtwfhdmvchdf2m3u3hlsd5tq5r",
+            "amount": "1"
+          }
+        ]
+      },
+      "result": {
+        "tx_hash": "c0d944db15446cf05e8db014685414c928d4d9a3e96aea229234be56eeae34c5",
+        "serialized_tx": "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"
+      }
+    },
     {
       "description": "Sample stake pool registration certificate with owner staking path account larger than 100",
       "parameters": {
diff --git a/core/src/apps/cardano/certificates.py b/core/src/apps/cardano/certificates.py
index bd34a058f9..8f40805c8f 100644
--- a/core/src/apps/cardano/certificates.py
+++ b/core/src/apps/cardano/certificates.py
@@ -117,7 +117,7 @@ def _validate_pool_parameters(
     assert_certificate_cond(len(pool_parameters.vrf_key_hash) == VRF_KEY_HASH_SIZE)
     assert_certificate_cond(0 <= pool_parameters.pledge <= LOVELACE_MAX_SUPPLY)
     assert_certificate_cond(0 <= pool_parameters.cost <= LOVELACE_MAX_SUPPLY)
-    assert_certificate_cond(pool_parameters.margin_numerator > 0)
+    assert_certificate_cond(pool_parameters.margin_numerator >= 0)
     assert_certificate_cond(pool_parameters.margin_denominator > 0)
     assert_certificate_cond(
         pool_parameters.margin_numerator <= pool_parameters.margin_denominator
diff --git a/tests/ui_tests/fixtures.json b/tests/ui_tests/fixtures.json
index 8db3354706..a2d91be8e4 100644
--- a/tests/ui_tests/fixtures.json
+++ b/tests/ui_tests/fixtures.json
@@ -10,6 +10,7 @@
 "cardano-test_sign_tx.py::test_cardano_sign_tx[mary_era_transaction_with_no_ttl-validity_start]": "db76676358164a3b3dab5148f09ba5515d079212366b79c44f95e2ba613abc71",
 "cardano-test_sign_tx.py::test_cardano_sign_tx[sample_stake_pool_registration_certificate]": "f56482d4a0f2c07fe04291a7d9c29ed4aedfd31e6a80fed1563d80e3a4c4005c",
 "cardano-test_sign_tx.py::test_cardano_sign_tx[sample_stake_pool_registration_certificate_wi-d3427614": "629ccaa5b660247843b366582c1bc505831c1800e028474a784b0f8b35fc473a",
+"cardano-test_sign_tx.py::test_cardano_sign_tx[sample_stake_pool_registration_with_zero_margin]": "802c6f1fcf232cf05ed64868d39913449918bc70fda39fcf9735f2d5db51ef3f",
 "cardano-test_sign_tx.py::test_cardano_sign_tx[simple_transaction_with_base_address_change_o-0c37e6dc": "a9bbc7137d32d71acc1b4d4b7c19aacf7ec8b63c06fe53c16759bf81f5d0ad96",
 "cardano-test_sign_tx.py::test_cardano_sign_tx[simple_transaction_with_base_address_change_output]": "3e55bbf1c01e9a889f2be7e3ae07db4348c13f6bdb6d746e7cb812a18329c9bb",
 "cardano-test_sign_tx.py::test_cardano_sign_tx[simple_transaction_with_base_script_address_c-466ef44c": "cdc9707b2c4ad61bb2037b93b68fac3aef071f1b1458a948a53a3997f3ffc131",