diff --git a/lnbits/helpers.py b/lnbits/helpers.py
index 9eefe365..cfff7bba 100644
--- a/lnbits/helpers.py
+++ b/lnbits/helpers.py
@@ -83,8 +83,8 @@ def url_for_vendored(abspath: str) -> str:
 def url_for(endpoint: str, external: Optional[bool] = False, **params: Any) -> str:
     base = g().base_url if external else ""
     url_params = "?"
-    for key in params:
-        url_params += f"{key}={params[key]}&"
+    for key, value in params.items():
+        url_params += f"{key}={value}&"
     url = f"{base}{endpoint}{url_params}"
     return url
 
diff --git a/tools/conv.py b/tools/conv.py
index f589eed4..1b35e25a 100644
--- a/tools/conv.py
+++ b/tools/conv.py
@@ -50,11 +50,13 @@ def check_db_versions(sqdb):
     postgres.execute("SELECT * FROM public.dbversions;")
     dbpost = dict(postgres.fetchall())
 
-    for key in dblite.keys():
-        if key in dblite and key in dbpost and dblite[key] != dbpost[key]:
-            raise Exception(
-                f"sqlite database version ({dblite[key]}) of {key} doesn't match postgres database version {dbpost[key]}"
-            )
+    for key, value in dblite.items():
+        if key in dblite and key in dbpost:
+            version = dbpost[key]
+            if value != version:
+                raise Exception(
+                    f"sqlite database version ({value}) of {key} doesn't match postgres database version {version}"
+                )
 
     connection = postgres.connection
     postgres.close()