diff --git a/src/grammars.hpp b/src/grammars.hpp
index 03f0c90..e86748c 100644
--- a/src/grammars.hpp
+++ b/src/grammars.hpp
@@ -262,7 +262,7 @@
     prepare_::name > space_separator > as<dataPath_>[RpcActionPath<AllowInput::Yes>{}];
 
 auto const exec_def =
-    exec_::name > -(space_separator > as<dataPath_>[RpcActionPath<AllowInput::No>{}]);
+    exec_::name > -(space_separator > -as<dataPath_>[RpcActionPath<AllowInput::No>{}]);
 
 auto const cancel_def =
     cancel_::name >> x3::attr(cancel_{});