diff --git a/src/pypath/annot.py b/src/pypath/annot.py
index 7b5ae95e9..e53c0b4c0 100644
--- a/src/pypath/annot.py
+++ b/src/pypath/annot.py
@@ -2305,7 +2305,7 @@ def to_dataframe(self, reference_set = None):
         
         df = pd.DataFrame(
             data = self.data,
-            index = self.uniprots,
+            index = self.reference_set,
             columns = colnames,
         )