diff -r 965127966331 -r d290b91e76b8 src/Pure/Syntax/printer.ML
--- a/src/Pure/Syntax/printer.ML	Mon Jan 13 18:20:35 1997 +0100
+++ b/src/Pure/Syntax/printer.ML	Mon Jan 13 18:24:40 1997 +0100
@@ -264,7 +264,7 @@
     and prefixT (_, a, [], _) = [Pretty.str a]
       | prefixT (c, _, args, p) =
           if c = Constant "_appl" orelse c = Constant "_applC" then
-            error "Syntax insufficient for printing prefix applications"
+            error "Syntax insufficient for printing prefix applications!"
           else astT (appT (c, args), p)
 
     and splitT 0 ([x], ys) = (x, ys)