diff --git a/fin_depo/data.py b/fin_depo/data.py
index f82d29a..2a0f228 100644
--- a/fin_depo/data.py
+++ b/fin_depo/data.py
@@ -44,6 +44,9 @@ class DepoSingle(Depo):
 
     _assets: Mapping[Asset, Decimal]
 
+    def __post_init__(self):
+        assert None not in self._assets
+
     def assets(self) -> Iterable[Asset]:
         return self._assets
 
@@ -58,6 +61,9 @@ class DepoGroup(Depo):
 
     nested: list[Depo]
 
+    def __post_init__(self):
+        assert None not in self.nested
+
     def assets(self) -> Iterable[Asset]:
         assets: set[Asset] = set()
         for nested_depo in self.nested:
diff --git a/fin_depo/defi_kraken.py b/fin_depo/defi_kraken.py
index 4e30861..249f799 100644
--- a/fin_depo/defi_kraken.py
+++ b/fin_depo/defi_kraken.py
@@ -59,4 +59,4 @@ def parse_asset_from_ticker(ticker: str) -> fin_defs.Asset:
     account = ticker.removesuffix('.HOLD')
     if account == 'ZEUR':
         return fin_defs.EUR
-    asset = fin_defs.WELL_KNOWN_SYMBOLS[account]
+    return fin_defs.WELL_KNOWN_SYMBOLS[account]