diff --git a/gintro.nimble b/gintro.nimble
index 090c77f..4183498 100644
--- a/gintro.nimble
+++ b/gintro.nimble
@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.4.18"
+version       = "0.4.20"
 author        = "Stefan Salewski"
 description = "High level GObject-Introspection based GTK3 bindings"
 license       = "MIT"
diff --git a/tests/gen.nim b/tests/gen.nim
index 5aee861..8e830e0 100644
--- a/tests/gen.nim
+++ b/tests/gen.nim
@@ -1,5 +1,5 @@
 # High level gobject-introspection based GTK3 bindings for the Nim programming language
-# v 0.4.18 2019-APR-27
+# v 0.4.20 2019-JUN-05
 # (c) S. Salewski 2018
 
 # https://wiki.gnome.org/Projects/GObjectIntrospection
@@ -733,7 +733,7 @@ proc writeMethod(info: GIBaseInfo; minfo: GIFunctionInfo; genProxy = false) =
                 else:
                   echo "Caution: No free/unref found for ", ' ', " (", sym, ')' # Mostly missing cairo functions...
               else:
-                assert not fixedDestroyNames.contains(sym)
+                assert (not fixedDestroyNames.contains(sym)) # missing outer () reported by Christian Ulrich, thanks.
                 freeMeName = $gBaseInfoGetName(freeMe)
               if sym == "g_closure_new_simple" or sym == "g_closure_new_object": freeMeName = "unref" # TODO GI bug?
               assert(gCallableInfoGetCallerOwns(minfo) in {GITransfer.EVERYTHING, GITransfer.NOTHING})