diff --git a/src/first-mate-helpers.js b/src/first-mate-helpers.js
index 826c47fa0..0ca312834 100644
--- a/src/first-mate-helpers.js
+++ b/src/first-mate-helpers.js
@@ -2,10 +2,10 @@ module.exports = {
   fromFirstMateScopeId (firstMateScopeId) {
     let atomScopeId = -firstMateScopeId
     if ((atomScopeId & 1) === 0) atomScopeId--
-    return atomScopeId
+    return atomScopeId + 256
   },
 
   toFirstMateScopeId (atomScopeId) {
-    return -atomScopeId
+    return -(atomScopeId - 256)
   }
 }
diff --git a/src/text-editor.coffee b/src/text-editor.coffee
index 8b171eb67..4864663fe 100644
--- a/src/text-editor.coffee
+++ b/src/text-editor.coffee
@@ -214,7 +214,7 @@ class TextEditor extends Model
     @disposables.add new Disposable =>
       cancelIdleCallback(@backgroundWorkHandle) if @backgroundWorkHandle?
 
-    @displayLayer.addTextDecorationLayer(@tokenizedBuffer)
+    @displayLayer.setTextDecorationLayer(@tokenizedBuffer)
     @defaultMarkerLayer = @displayLayer.addMarkerLayer()
     @disposables.add(@defaultMarkerLayer.onDidDestroy =>
       @assert(false, "defaultMarkerLayer destroyed at an unexpected time")