diff --git a/geomagio/DerivedTimeseriesFactory.py b/geomagio/DerivedTimeseriesFactory.py
index 94abbe596858ede6392218e8c0fb798c1afd2a43..273b18dd25a8d8409c45e69cf0274c03bd003647 100644
--- a/geomagio/DerivedTimeseriesFactory.py
+++ b/geomagio/DerivedTimeseriesFactory.py
@@ -204,6 +204,4 @@ class DerivedTimeseriesFactory(TimeseriesFactory):
 def get_missing(input: Stream, desired: List[str]) -> List[str]:
     """Return missing channels from input"""
     present = TimeseriesUtility.get_channels(stream=input)
-    if present is None:
-        return desired
     return list(set(desired).difference(set(present)))
diff --git a/geomagio/TimeseriesUtility.py b/geomagio/TimeseriesUtility.py
index e0729c21b81796707a06cff1184765aeab5be29c..79cc482636837657bbcd7cab97a4cbc5a81de92f 100644
--- a/geomagio/TimeseriesUtility.py
+++ b/geomagio/TimeseriesUtility.py
@@ -304,7 +304,7 @@ def get_channels(stream):
         channel = trace.stats.channel
         if channel:
             channels[channel] = True
-    return [ch for ch in channels]
+    return [ch for ch in channels] or []
 
 
 def get_trace_value(traces, time, default=None):