diff --git a/plot_single_transmission_paper.py b/plot_single_transmission_paper.py
index b2268e4..dcb6ad1 100755
--- a/plot_single_transmission_paper.py
+++ b/plot_single_transmission_paper.py
@@ -84,6 +84,7 @@ if __name__ == "__main__":
             dtype=dict(is_retranmission=bool, is_dup_ack=bool),
         )
 
+        transmission_df = transmission_df.set_index("datetime")
         transmission_df.index = pd.to_datetime(transmission_df.index)
         transmission_df = transmission_df.sort_index()