diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index f5b2b3169d6d..7a33295fcb83 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -2779,7 +2779,7 @@ PresShell::NotifyDestroyingFrame(nsIFrame* aFrame)
   }
 }
 
-already_AddRefed<nsCaret> PresShell::GetCaret()
+already_AddRefed<nsCaret> PresShell::GetCaret() const
 {
   nsCaret* caret = mCaret;
   NS_IF_ADDREF(caret);