Index: libcfa/src/concurrency/mutex_stmt.hfa
===================================================================
--- libcfa/src/concurrency/mutex_stmt.hfa	(revision aca0d2f510429843eb53e3fd4cb1160ade5d68d3)
+++ libcfa/src/concurrency/mutex_stmt.hfa	(revision dd3576b74599ea86e0c5b495315a213a3519cd0b)
@@ -4,5 +4,6 @@
 //-----------------------------------------------------------------------------
 // is_lock
-trait is_lock(L & | sized(L)) {
+forall(L & | sized(L))
+trait is_lock {
 	// For acquiring a lock
 	void lock( L & );