diff --git a/app/src/main/java/io/legado/app/ui/book/read/page/delegate/SimulationPageDelegate.kt b/app/src/main/java/io/legado/app/ui/book/read/page/delegate/SimulationPageDelegate.kt
index 8a66d715e..55a4a5209 100644
--- a/app/src/main/java/io/legado/app/ui/book/read/page/delegate/SimulationPageDelegate.kt
+++ b/app/src/main/java/io/legado/app/ui/book/read/page/delegate/SimulationPageDelegate.kt
@@ -487,8 +487,8 @@ class SimulationPageDelegate(pageView: PageView) : HorizontalPageDelegate(pageVi
         } else {
             pageView.height
         }
-        mIsRT_LB = (mCornerX == 0 && mCornerY == pageView.height
-                || mCornerX == pageView.width && mCornerY == 0)
+        mIsRT_LB = (mCornerX == 0 && mCornerY == pageView.height)
+                || (mCornerX == pageView.width && mCornerY == 0)
     }
 
     private fun calcPoints() {