diff --git a/bin/summary_hash.py b/bin/summary_hash.py
index 11d1e91..d74fa32 100755
--- a/bin/summary_hash.py
+++ b/bin/summary_hash.py
@@ -241,7 +241,7 @@ def htodemux_summary(htodemux_res, raw_adata, raw_mudata):
 
         if raw_mudata is not None:
             mudata = raw_mudata.copy()
-            mudata['rna'].obs = mudata['rna'].obs.merge(htodemux_assign, left_index=True, right_on='Barcode', how='left').set_index('Barcode')
+            mudata['rna'].obs = mudata['rna'].obs.merge(htodemux_assign, left_index=True, right_index=True, how='left')
             mudata['rna'].obs.rename(columns={mudata['rna'].obs.columns[0]: 'donor'}, inplace=True)
             mudata['rna'].obs.donor = mudata['rna'].obs.donor.fillna("negative")
             mudata['rna'].obs.donor = mudata['rna'].obs.donor.astype(str)