diff --git a/languages/perl6/src/classes/List.pir b/languages/perl6/src/classes/List.pir
index 46eb4a8..23dd57f 100644
--- a/languages/perl6/src/classes/List.pir
+++ b/languages/perl6/src/classes/List.pir
@@ -479,20 +479,49 @@ Return a list of Pair(index, value) elements for the invocant.
     .param pmc expression
     .local pmc retv
     .local pmc iter
-    .local pmc block_res
-    .local pmc block_arg
+    .local pmc elem
+    .local pmc args
+    .local int i, arity
+
+    arity = expression.'arity'()
+    if arity < 2 goto error
 
     iter = self.'iterator'()
     unless iter goto empty
     retv = shift iter
   loop:
     unless iter goto done
-    block_arg = shift iter
-    block_res = expression(retv, block_arg)
+
+    # Create arguments for closure
+    args = new 'ResizablePMCArray'
+    # Start with 1. First argument is result of previous call
+    i = 1
+
+  args_loop:
+    if i == arity goto invoke
+    unless iter goto elem_undef
+    elem = shift iter
+    goto push_elem
+  elem_undef:
+    elem = new 'Failure'
+  
+  push_elem:
+    push args, elem
+    inc i
+    goto args_loop
+
+  invoke:
+    retv = expression(retv, args :flat)
     goto loop
 
   empty:
     retv = new 'Undef'
+    goto done
+
+  error:
+    'die'('Cannot reduce() using a unary or nullary function.')
+    goto done
+    
   done:
     .return(retv)
 .end