diff --git a/plot_transmission_timeline.py b/plot_transmission_timeline.py
index 87a320f..66b22d3 100755
--- a/plot_transmission_timeline.py
+++ b/plot_transmission_timeline.py
@@ -187,7 +187,7 @@ if __name__ == "__main__":
 
     cmap = matplotlib.cm.get_cmap("Set3")
     for c in transmission_df["cellID"].unique():
-        bounds = transmission_df[["cellID"]].groupby("cellID").agg(["min", "max"]).loc[c]
+        bounds = transmission_df.groupby("cellID").agg(["min", "max"]).loc[c]
         host.axvspan(bounds.min(), bounds.max() + 1, alpha=0.3, color=cmap.colors[c])