diff --git a/shell/Ui/BarIconButton.qml b/shell/Ui/BarIconButton.qml
index e2ea6358..e2af8808 100644
--- a/shell/Ui/BarIconButton.qml
+++ b/shell/Ui/BarIconButton.qml
@@ -10,6 +10,7 @@ WidgetButton {
   property real opticalSize: Style.bar.iconCanvas
   property bool debugOpticalBounds: Quickshell.env("OMARCHY_DEBUG_BAR_ICONS") === "1"
   readonly property real opticalCenterErrorX: glyph.visible ? glyph.paintedCenterX - opticalCanvas.width / 2 : 0
+  readonly property real glyphPaintedWidth: glyph.visible ? glyph.tightWidth : 0
   readonly property real glyphBaselineY: glyph.visible ? glyph.baselineY : 0
   readonly property int glyphFontSize: glyph.visible ? glyph.renderedFontSize : 0
 
diff --git a/shell/plugins/panels/power/Panel.qml b/shell/plugins/panels/power/Panel.qml
index 6c2fe91a..e03c31f6 100644
--- a/shell/plugins/panels/power/Panel.qml
+++ b/shell/plugins/panels/power/Panel.qml
@@ -17,6 +17,10 @@ Panel {
   property int profileIndex: 0
   property bool cursorActive: false
   readonly property bool showPercentage: setting("showPercentage", false) === true
+  // With the percentage shown the button paints a text block wider than an
+  // icon, so the open-panel mark takes the painted width instead of the
+  // icon-sized fraction of the slot the fallback assumes.
+  readonly property real openPanelIndicatorWidth: showPercentage && !button.vertical ? button.glyphPaintedWidth : 0
   readonly property bool batteryPresent: {
     var device = UPower.displayDevice
     return !!(device && device.isPresent)
diff --git a/test/shell.d/power-test.sh b/test/shell.d/power-test.sh
index c51cd46a..4d24f88f 100644
--- a/test/shell.d/power-test.sh
+++ b/test/shell.d/power-test.sh
@@ -45,4 +45,5 @@ assertEqual(
 assert(/if \(b === Qt\.RightButton\) root\.togglePercentage\(\)/.test(panelSource), 'power right click toggles the bar percentage')
 assert(/Object\.assign\([^\n]+showPercentage: !root\.showPercentage[^\n]+\)[\s\S]*updateEntryInline/.test(panelSource), 'power persists the bar percentage setting')
 assert(/Math\.round\(root\.batteryFraction \* 100\) \+ "% " \+ root\.batteryIcon\(\)/.test(panelSource), 'power places the percentage before the battery icon')
+assert(/openPanelIndicatorWidth:.*showPercentage.*button\.glyphPaintedWidth : 0/.test(panelSource), 'power spans the open-panel mark across the painted percentage block')
 JS