diff --git a/luametalatex-back-pdf.lua b/luametalatex-back-pdf.lua
index 74afa30..dff1b64 100644
--- a/luametalatex-back-pdf.lua
+++ b/luametalatex-back-pdf.lua
@@ -105,7 +105,7 @@ callback.register("stop_run", function()
         destnames[k] = obj .. ' 0 R'
       end
     else
-      texio.write_nl("Warning: Undefined destination %q", tostring(k))
+      texio.write_nl(string.format("Warning: Undefined destination %q", tostring(k)))
     end
   end
   if next(destnames) then
diff --git a/luametalatex-microtype.sty b/luametalatex-microtype.sty
index de796d0..b7b71f9 100644
--- a/luametalatex-microtype.sty
+++ b/luametalatex-microtype.sty
@@ -18,7 +18,7 @@
   \endgroup
   \def\noexpand\pickup@font{!
     \unexpanded\expandafter{\pickup@font
-      \expandafter\expandafter\expandafter\luametalatex@@setexpansion\csname pickup@font@@hook@luametalatex@microtype@\the\fontid\font@name\endcsname{0}{0}{0}\relax
+      \expandafter\expandafter\expandafter\luametalatex@@setexpansion\csname pickup@font@@hook@luametalatex@microtype@\the\fontid\font@name\endcsname{-1}{-1}{-1}\relax
     }!
   }!
   \noexpand\luametalatex@@everyjobandnow{\noexpand\directlua{!