diff --git a/libs/ardour/ardour/region.h b/libs/ardour/ardour/region.h
index a77d92fd9e..54cfd57fea 100644
--- a/libs/ardour/ardour/region.h
+++ b/libs/ardour/ardour/region.h
@@ -388,7 +388,7 @@ class LIBARDOUR_API Region
 	bool verify_start (framepos_t);
 	bool verify_start_and_length (framepos_t, framecnt_t&);
 	bool verify_start_mutable (framepos_t&_start);
-	bool verify_length (framecnt_t);
+	bool verify_length (framecnt_t&);
 
 	virtual void recompute_at_start () = 0;
 	virtual void recompute_at_end () = 0;
diff --git a/libs/ardour/region.cc b/libs/ardour/region.cc
index 1784cdbf3c..2e5d95be9f 100644
--- a/libs/ardour/region.cc
+++ b/libs/ardour/region.cc
@@ -1515,7 +1515,7 @@ Region::source_length(uint32_t n) const
 }
 
 bool
-Region::verify_length (framecnt_t len)
+Region::verify_length (framecnt_t& len)
 {
 	if (source() && (source()->destructive() || source()->length_mutable())) {
 		return true;