diff --git a/tgt-vhdl/vhdl.conf b/tgt-vhdl/vhdl.conf
index 0d382d395..a331b8ca5 100644
--- a/tgt-vhdl/vhdl.conf
+++ b/tgt-vhdl/vhdl.conf
@@ -1,3 +1,4 @@
 functor:cprop
 functor:nodangle
 flag:DLL=vhdl.tgt
+flag:DISABLE_CONCATZ_GENERATION=true