diff --git a/spec/text-editor-component-spec.js b/spec/text-editor-component-spec.js
index ef65a5738..bd03863ef 100644
--- a/spec/text-editor-component-spec.js
+++ b/spec/text-editor-component-spec.js
@@ -195,6 +195,21 @@ describe('TextEditorComponent', () => {
       expect(lineNodeForScreenRow(component, 7)).toBe(lineNode)
     })
 
+    it('updates lines numbers when a row\'s foldability changes (regression)', async () => {
+      const {component, element, editor} = buildComponent({text: 'abc\n'})
+      editor.setCursorBufferPosition([1, 0])
+      await component.getNextUpdatePromise()
+      expect(lineNumberNodeForScreenRow(component, 0).querySelector('.foldable')).toBeNull()
+
+      editor.insertText('  def')
+      await component.getNextUpdatePromise()
+      expect(lineNumberNodeForScreenRow(component, 0).querySelector('.foldable')).toBeDefined()
+
+      editor.undo()
+      await component.getNextUpdatePromise()
+      expect(lineNumberNodeForScreenRow(component, 0).querySelector('.foldable')).toBeNull()
+    })
+
     it('renders dummy vertical and horizontal scrollbars when content overflows', async () => {
       const {component, element, editor} = buildComponent({height: 100, width: 100})
       const verticalScrollbar = component.refs.verticalScrollbar.element
diff --git a/src/text-editor-component.js b/src/text-editor-component.js
index f0e90e767..aeead049c 100644
--- a/src/text-editor-component.js
+++ b/src/text-editor-component.js
@@ -823,11 +823,10 @@ class TextEditorComponent {
     const endRow = this.getRenderedEndRow()
     const renderedRowCount = this.getRenderedRowCount()
 
-    const {keys, softWrappedFlags, foldableFlags} = this.lineNumbersToRender
     const bufferRows = model.bufferRowsForScreenRows(startRow, endRow - 1)
-    this.lineNumbersToRender.bufferRows = bufferRows
-    keys.length = renderedRowCount
-    foldableFlags.length = renderedRowCount
+    const keys = new Array(endRow - startRow)
+    const foldableFlags = new Array(endRow - startRow)
+    const softWrappedFlags = new Array(endRow - startRow)
 
     let previousBufferRow = (startRow > 0) ? model.bufferRowForScreenRow(startRow - 1) : -1
     let softWrapCount = 0
@@ -847,6 +846,11 @@ class TextEditorComponent {
       }
       previousBufferRow = bufferRow
     }
+
+    this.lineNumbersToRender.bufferRows = bufferRows
+    this.lineNumbersToRender.keys = keys
+    this.lineNumbersToRender.foldableFlags = foldableFlags
+    this.lineNumbersToRender.softWrappedFlags = softWrappedFlags
   }
 
   queryMaxLineNumberDigits () {