diff --git a/compound.hh b/compound.hh
index 2f7c9b11e8..4d90146fec 100644
--- a/compound.hh
+++ b/compound.hh
@@ -58,6 +58,10 @@ public:
         return _types;
     }
 
+    bool is_singular() const {
+        return _types.size() == 1;
+    }
+
     prefix_type as_prefix() {
         return prefix_type(_types);
     }