diff --git a/lib/modules/Thread.pmod b/lib/modules/Thread.pmod
index c5cd1c6a66047c20f6f4a2d89fb9d5e2281ae52d..019b9718ff1b9058c49ffc455b7c8d0fb2f547a2 100644
--- a/lib/modules/Thread.pmod
+++ b/lib/modules/Thread.pmod
@@ -1,5 +1,5 @@
-constant Mutex=__builtin.Mutex;
-constant Condition=__builtin.Condition;
+constant Mutex=__builtin.mutex;
+constant Condition=__builtin.condition;
 
 class Fifo {
   inherit Condition : r_cond;