diff --git a/src/Cursor.cpp b/src/Cursor.cpp
index 674075a8ec..eb23d79533 100644
--- a/src/Cursor.cpp
+++ b/src/Cursor.cpp
@@ -645,7 +645,7 @@ namespace lyx {
 //#define FILEDEBUG 1
 
 
-bool Cursor::isInside(Inset const * p)
+bool Cursor::isInside(Inset const * p) const
 {
 	for (size_t i = 0; i != depth(); ++i)
 		if (&operator[](i).inset() == p)
diff --git a/src/Cursor.h b/src/Cursor.h
index d75891b7ef..0d49502ef1 100644
--- a/src/Cursor.h
+++ b/src/Cursor.h
@@ -330,7 +330,7 @@ public:
 	// selection in given cell of atom
 	void handleNest(MathAtom const & at, int cell = 0);
 	///
-	bool isInside(Inset const *);
+	bool isInside(Inset const *) const;
 
 	/// make sure cursor position is valid
 	/// FIXME: It does a subset of fixIfBroken. Maybe merge them?