diff --git a/piker/ui/_chart.py b/piker/ui/_chart.py
index 71280fa2..f8028d9b 100644
--- a/piker/ui/_chart.py
+++ b/piker/ui/_chart.py
@@ -547,6 +547,7 @@ class LinkedSplits(QWidget):
             if sidepane:
                 # TODO: use a "panes" collection to manage this?
                 sidepane.setMinimumWidth(self.chart.sidepane.width())
+                sidepane.setMaximumWidth(self.chart.sidepane.width())
 
             self.splitter.addWidget(qframe)