diff --git a/homeassistant/components/alpha_vantage/sensor.py b/homeassistant/components/alpha_vantage/sensor.py
index 534383f0bbf..02c6958e0da 100644
--- a/homeassistant/components/alpha_vantage/sensor.py
+++ b/homeassistant/components/alpha_vantage/sensor.py
@@ -128,7 +128,7 @@ class AlphaVantageSensor(SensorEntity):
         self._attr_native_unit_of_measurement = symbol.get(CONF_CURRENCY, self._symbol)
         self._attr_icon = ICONS.get(symbol.get(CONF_CURRENCY, "USD"))
 
-    def update(self):
+    def update(self) -> None:
         """Get the latest data and updates the states."""
         _LOGGER.debug("Requesting new data for symbol %s", self._symbol)
         all_values, _ = self._timeseries.get_intraday(self._symbol)
@@ -144,7 +144,7 @@ class AlphaVantageSensor(SensorEntity):
                 ATTR_LOW: values["3. low"],
             }
             if isinstance(values, dict)
-            else None
+            else {}
         )
         _LOGGER.debug("Received new values for symbol %s", self._symbol)
 
@@ -167,7 +167,7 @@ class AlphaVantageForeignExchange(SensorEntity):
         self._attr_icon = ICONS.get(self._from_currency, "USD")
         self._attr_native_unit_of_measurement = self._to_currency
 
-    def update(self):
+    def update(self) -> None:
         """Get the latest data and updates the states."""
         _LOGGER.debug(
             "Requesting new data for forex %s - %s",
@@ -187,7 +187,7 @@ class AlphaVantageForeignExchange(SensorEntity):
                 CONF_TO: self._to_currency,
             }
             if values is not None
-            else None
+            else {}
         )
 
         _LOGGER.debug(