diff --git a/rust/src/parser.rs b/rust/src/parser.rs
index 06a48db..d5334df 100644
--- a/rust/src/parser.rs
+++ b/rust/src/parser.rs
@@ -47,8 +47,7 @@ peg::parser! {
         rule funcall() -> Expr<'input>
             = i:id() "(" _ e:(expr() ** ("," _)) ")" _ { Expr::Funcall(i, e) }
         rule funcdef() -> Expr<'input>
-            = i:id()? "->" _ e:expr() { Expr::Funcdef(i, Box::new(e)) } /
-              i:id()? "->" _ b:block() { Expr::Funcdef(i, Box::new(b)) }
+            = i:id()? "->" _ e:(expr() / block()) { Expr::Funcdef(i, Box::new(e)) }
 
         rule letter()
             = ['A'..='Z'] / ['a'..='z']