diff --git a/app/config.py b/app/config.py
index be424cf2..9d08083e 100644
--- a/app/config.py
+++ b/app/config.py
@@ -375,5 +375,8 @@ ALIAS_LIMIT = os.environ.get("ALIAS_LIMIT") or "100/day;50/hour;5/minute"
 
 ENABLE_SPAM_ASSASSIN = "ENABLE_SPAM_ASSASSIN" in os.environ
 
-HIBP_SCAN_INTERVAL_DAYS = os.environ.get("HIBP_SCAN_INTERVAL_DAYS") or 7
-HIBP_API_KEYS = sl_getenv("HIBP_API_KEYS", list) or []
\ No newline at end of file
+try:
+    HIBP_SCAN_INTERVAL_DAYS = int(os.environ.get("HIBP_SCAN_INTERVAL_DAYS"))
+except Exception:
+    HIBP_SCAN_INTERVAL_DAYS = 7
+HIBP_API_KEYS = sl_getenv("HIBP_API_KEYS", list) or []
diff --git a/app/models.py b/app/models.py
index b38dfde8..ff776ff3 100644
--- a/app/models.py
+++ b/app/models.py
@@ -25,7 +25,7 @@ from app.config import (
     FIRST_ALIAS_DOMAIN,
     DISABLE_ONBOARDING,
     UNSUBSCRIBER,
-    HIBP_SCAN_INTERVAL_DAYS
+    HIBP_SCAN_INTERVAL_DAYS,
 )
 from app.errors import AliasInTrashError
 from app.extensions import db
@@ -1089,7 +1089,9 @@ class Alias(db.Model, ModelMixin):
         return False
 
     def needs_hibp_scan(self):
-        return self.hibp_last_check is None or (self.hibp_last_check < arrow.now().shift(days=-HIBP_SCAN_INTERVAL_DAYS))
+        return self.hibp_last_check is None or (
+            self.hibp_last_check < arrow.now().shift(days=-HIBP_SCAN_INTERVAL_DAYS)
+        )
 
     @classmethod
     def create(cls, **kw):
@@ -2021,15 +2023,17 @@ class AliasMailbox(db.Model, ModelMixin):
 class AliasHibp(db.Model, ModelMixin):
     __tablename__ = "alias_hibp"
 
-    __table_args__ = (
-        db.UniqueConstraint("alias_id", "hibp_id", name="uq_alias_hibp"),
-    )
+    __table_args__ = (db.UniqueConstraint("alias_id", "hibp_id", name="uq_alias_hibp"),)
 
     alias_id = db.Column(db.Integer(), db.ForeignKey("alias.id"))
     hibp_id = db.Column(db.String(), db.ForeignKey("hibp.id"))
 
-    alias = db.relationship("Alias", backref=db.backref("alias_hibp", cascade="all, delete-orphan"))
-    hibp = db.relationship("Hibp", backref=db.backref("alias_hibp", cascade="all, delete-orphan"))
+    alias = db.relationship(
+        "Alias", backref=db.backref("alias_hibp", cascade="all, delete-orphan")
+    )
+    hibp = db.relationship(
+        "Hibp", backref=db.backref("alias_hibp", cascade="all, delete-orphan")
+    )
 
 
 class DirectoryMailbox(db.Model, ModelMixin):
diff --git a/cron.py b/cron.py
index b6b64a82..fda5d4ef 100644
--- a/cron.py
+++ b/cron.py
@@ -17,7 +17,7 @@ from app.config import (
     EMAIL_SERVERS_WITH_PRIORITY,
     URL,
     AlERT_WRONG_MX_RECORD_CUSTOM_DOMAIN,
-    HIBP_API_KEYS
+    HIBP_API_KEYS,
 )
 from app.dns_utils import get_mx_domains
 from app.email_utils import (
@@ -53,7 +53,7 @@ from app.models import (
     SLDomain,
     DeletedAlias,
     DomainDeletedAlias,
-    Hibp
+    Hibp,
 )
 from app.utils import sanitize_email
 from server import create_app
@@ -776,7 +776,7 @@ def check_hibp():
     LOG.d("Updating list of known breaches")
     r = requests.get("https://haveibeenpwned.com/api/v3/breaches")
     for entry in r.json():
-        Hibp.get_or_create(id=entry['Name'])
+        Hibp.get_or_create(id=entry["Name"])
 
     db.session.commit()
 
@@ -787,26 +787,34 @@ def check_hibp():
             continue
 
         # Only one request per API key per 1.5 seconds
-        if (api_key_index >= len(HIBP_API_KEYS)):
+        if api_key_index >= len(HIBP_API_KEYS):
             api_key_index = 0
             sleep(1.5)
 
         request_headers = {
             "user-agent": "SimpleLogin",
-            "hibp-api-key": HIBP_API_KEYS[api_key_index]
+            "hibp-api-key": HIBP_API_KEYS[api_key_index],
         }
-        r = requests.get(f"https://haveibeenpwned.com/api/v3/breachedaccount/{urllib.parse.quote(alias.email)}", headers=request_headers)
+        r = requests.get(
+            f"https://haveibeenpwned.com/api/v3/breachedaccount/{urllib.parse.quote(alias.email)}",
+            headers=request_headers,
+        )
 
         api_key_index += 1
 
         if r.status_code == 200:
             # Breaches found
-            alias.hibp_breaches = [Hibp.get_by(id=entry['Name']) for entry in r.json()]
+            alias.hibp_breaches = [Hibp.get_by(id=entry["Name"]) for entry in r.json()]
         elif r.status_code == 404:
             # No breaches found
             alias.hibp_breaches = []
         else:
-            LOG.error("An error occured while checking alias %s: %s - %s", alias, r.status_code, r.text)
+            LOG.error(
+                "An error occured while checking alias %s: %s - %s",
+                alias,
+                r.status_code,
+                r.text,
+            )
             continue
 
         alias.hibp_last_check = arrow.utcnow()
@@ -836,7 +844,7 @@ if __name__ == "__main__":
             "sanity_check",
             "delete_old_monitoring",
             "check_custom_domain",
-            "check_hibp"
+            "check_hibp",
         ],
     )
     args = parser.parse_args()
diff --git a/server.py b/server.py
index 2028ffdc..841a3f57 100644
--- a/server.py
+++ b/server.py
@@ -299,9 +299,7 @@ def fake_data():
     db.session.commit()
 
     # example@example.com is in a LOT of data breaches
-    Alias.create(
-        email="example@example.com", user_id=user.id, mailbox_id=m1.id
-    )
+    Alias.create(email="example@example.com", user_id=user.id, mailbox_id=m1.id)
 
     for i in range(3):
         if i % 2 == 0: