diff --git a/spec/text-editor-spec.js b/spec/text-editor-spec.js
index 55bc68935..2f7e25f76 100644
--- a/spec/text-editor-spec.js
+++ b/spec/text-editor-spec.js
@@ -6613,17 +6613,6 @@ describe('TextEditor', () => {
     })
   })
 
-  describe('when the editor is constructed with the grammar option set', () => {
-    beforeEach(async () => {
-      await atom.packages.activatePackage('language-coffee-script')
-    })
-
-    it('sets the grammar', () => {
-      editor = new TextEditor({grammar: atom.grammars.grammarForScopeName('source.coffee')})
-      expect(editor.getGrammar().name).toBe('CoffeeScript')
-    })
-  })
-
   describe('softWrapAtPreferredLineLength', () => {
     it('soft wraps the editor at the preferred line length unless the editor is narrower or the editor is mini', () => {
       editor.update({
diff --git a/src/text-editor.js b/src/text-editor.js
index f1ec52297..c179737b1 100644
--- a/src/text-editor.js
+++ b/src/text-editor.js
@@ -4437,10 +4437,10 @@ class TextEditor {
   toggleLineCommentForBufferRow (row) { this.toggleLineCommentsForBufferRows(row, row) }
 
   toggleLineCommentsForBufferRows (start, end) {
-    let {
-      commentStartString,
-      commentEndString
-    } = this.buffer.getLanguageMode().commentStringsForPosition(Point(start, 0))
+    const languageMode = this.buffer.getLanguageMode()
+    let {commentStartString, commentEndString} =
+      languageMode.commentStringsForPosition &&
+      languageMode.commentStringsForPosition(Point(start, 0)) || {}
     if (!commentStartString) return
     commentStartString = commentStartString.trim()