diff --git a/src/CutAndPaste.cpp b/src/CutAndPaste.cpp
index 77b0ff2fae..2450e0fc5c 100644
--- a/src/CutAndPaste.cpp
+++ b/src/CutAndPaste.cpp
@@ -392,8 +392,8 @@ docstring grabAndEraseSelection(Cursor & cur)
 }
 
 
-void switchBetweenClasses(TextClassPtr oldone, TextClassPtr newone, 
-		InsetText & in, ErrorList & errorlist)
+void switchBetweenClasses(TextClassPtr const & oldone, 
+		TextClassPtr const & newone, InsetText & in, ErrorList & errorlist)
 {
 	errorlist.clear();