diff --git a/src/ui/popup_window.cpp b/src/ui/popup_window.cpp
index f993e6491..c8938bbc2 100644
--- a/src/ui/popup_window.cpp
+++ b/src/ui/popup_window.cpp
@@ -43,10 +43,6 @@ PopupWindow::~PopupWindow()
   stopFilteringMessages();
 }
 
-/**
- * @param region The new hot-region. This pointer is holded by the @a widget.
- * So you cannot destroy it after calling this routine.
- */
 void PopupWindow::setHotRegion(const gfx::Region& region)
 {
   startFilteringMessages();
diff --git a/src/ui/popup_window.h b/src/ui/popup_window.h
index b60a5fa4d..1b3750774 100644
--- a/src/ui/popup_window.h
+++ b/src/ui/popup_window.h
@@ -30,6 +30,8 @@ namespace ui {
                 EnterBehavior enterBehavior = EnterBehavior::CloseOnEnter);
     ~PopupWindow();
 
+    // Sets the hot region. This region indicates the area where the
+    // mouse can be located and the window will be kept open.
     void setHotRegion(const gfx::Region& region);
     void setClickBehavior(ClickBehavior behavior);
     void setEnterBehavior(EnterBehavior behavior);