diff --git a/lib/minimap-selection-view.js b/lib/minimap-selection-view.js
index 4de0aec..98d5620 100644
--- a/lib/minimap-selection-view.js
+++ b/lib/minimap-selection-view.js
@@ -7,13 +7,12 @@ class MinimapSelectionView {
 		this.minimap = minimap
 		const editor = this.minimap.getTextEditor()
 
-		this.subscriptions = new CompositeDisposable()
-
-		this.subscriptions.add(editor.onDidAddCursor(this.handleSelection))
-		this.subscriptions.add(editor.onDidChangeCursorPosition(this.handleSelection))
-		this.subscriptions.add(editor.onDidRemoveCursor(this.handleSelection))
-		this.subscriptions.add(atom.config.observe('minimap-selection.outlineSelection', this.handleSelection))
-
+		this.subscriptions = new CompositeDisposable(
+			editor.onDidAddCursor(this.handleSelection),
+			editor.onDidChangeCursorPosition(this.handleSelection),
+			editor.onDidRemoveCursor(this.handleSelection),
+			atom.config.observe('minimap-selection.outlineSelection', this.handleSelection),
+		)
 		this.handleSelection()
 	}
 
diff --git a/lib/minimap-selection.js b/lib/minimap-selection.js
index 9a5a104..11f0f60 100644
--- a/lib/minimap-selection.js
+++ b/lib/minimap-selection.js
@@ -16,7 +16,7 @@ module.exports = {
 
 	activate () {
 		this.active = false
-		this.views = {}
+		this.views = new Map()
 		require('atom-package-deps').install('minimap-selection')
 	},
 
@@ -42,11 +42,11 @@ module.exports = {
 			const minimap = o.view ? o.view : o
 			const selectionView = new MinimapSelectionView(minimap)
 
-			this.views[minimap.id] = selectionView
+			this.views.set(minimap.id, selectionView)
 
 			const disposable = minimap.onDidDestroy(() => {
 				selectionView.destroy()
-				delete this.views[minimap.id]
+				this.views.delete(minimap.id)
 				disposable.dispose()
 			})
 		})
@@ -54,10 +54,10 @@ module.exports = {
 
 	deactivatePlugin () {
 		if (!this.active) { return }
-		for (const id in this.views) { const view = this.views[id]; view.destroy() }
+		const views = this.views.values()
+		for (const view of views) { view.destroy() }
 		this.active = false
-		this.views = {}
-
+		this.views.clear()
 		this.subscription.dispose()
 	},
 }
diff --git a/styles/minimap-selection.less b/styles/minimap-selection.less
index 92bb771..dfed431 100644
--- a/styles/minimap-selection.less
+++ b/styles/minimap-selection.less
@@ -4,14 +4,19 @@
 // for a full listing of what's available.
 @import "ui-variables";
 
+@contain_all: layout size paint style;
+
 .minimap-selection .region {
+  contain: @contain_all;
   background: @background-color-selected;
 }
 
 .minimap-selection .region-outline {
+  contain: @contain_all;
   background: @text-color;
 }
 
 .minimap-selection .cursor-line {
+  contain: @contain_all;
   background: @background-color-selected;
 }