diff --git a/gtk/gtkcsspositionvalue.c b/gtk/gtkcsspositionvalue.c
index 6f33de73a1..09c845d2fc 100644
--- a/gtk/gtkcsspositionvalue.c
+++ b/gtk/gtkcsspositionvalue.c
@@ -224,7 +224,10 @@ _gtk_css_position_value_parse (GtkCssParser *parser)
             return NULL;
         }
       else
-        return NULL;
+        {
+          _gtk_css_parser_error (parser, "Unrecognized position value");
+          return NULL;
+        }
     }
 
   for (second = 0; names[second].name != NULL; second++)