diff --git a/aliby/io/omero.py b/aliby/io/omero.py
index d9677af2cb1af1c42172eee4b5fecefd69955404..914b68ba4e655bb804c35afdc78e83563a2b3cb3 100644
--- a/aliby/io/omero.py
+++ b/aliby/io/omero.py
@@ -63,6 +63,8 @@ class Dataset(Argo):
                 for x in self.dataset.listAnnotations()
                 if isinstance(x, omero.gateway.FileAnnotationWrapper)
             }
+        if not len(self._files):
+            raise Exception("Exception:Metadata: Experiment has no annotation files.")
         return self._files
 
     @property