diff --git a/src/GF/Compile/PGFPretty.hs b/src/GF/Compile/PGFPretty.hs
index 26df0204d..ef69b710b 100644
--- a/src/GF/Compile/PGFPretty.hs
+++ b/src/GF/Compile/PGFPretty.hs
@@ -52,7 +52,7 @@ prCnc abstr name c = prAll prLinCat (lincats c) $$ prAll prLin (lins (expand c))
           pr p (R [t]) = pr p t
           pr p (R ts) = text "<" <+> hsep (punctuate (text ",") (map (pr 0) ts)) <+> text ">"
           pr p (P t1 t2) = prec p 3 (pr 3 t1 <> text "!" <> pr 3 t2)
-          pr p (S ts) = prec p 2 (hsep (map (pr 2) ts))
+          pr p (S ts) = prec p 2 (hsep (punctuate (text " ++") (map (pr 2) ts)))
           pr p (K (KS t)) = doubleQuotes (text t)
           pr p (V i) = text ("argv_" ++ show (i+1))
           pr p (C i) = text (show (i+1))
@@ -72,8 +72,8 @@ expand cnc = cnc { lins = Map.map (f "") (lins cnc) }
     -- FIXME: handle KP
     f :: String -> Term -> Term
     f w (R ts) = R (map (f w) ts)
-    f "" (P t1 t2) = P (f "" t1) (f "" t2)
-    f w (S []) = S []
+    f w (P t1 t2) = P (f w t1) (f w t2)
+    f w (S []) = S [K (KS w)]
     f w (S (t:ts)) = S (f w t : map (f "") ts)
     f w (FV ts) = FV (map (f w) ts)
     f w (W s t) = f (w++s) t