diff --git a/lib/core.fs b/lib/core.fs
index a23c798..956c5ee 100644
--- a/lib/core.fs
+++ b/lib/core.fs
@@ -17,7 +17,7 @@ s" Invalid argument" exception constant INVALID-ARGUMENT
 ;
 
 defined? roll [unless]
-    : roll ( wn ... w1 n -- w1 wn ... w2 )
+    : roll ( w[n-1] ... w0 n -- w0 w[n-2] ... w0 w[n-1] )
         dup 0<= if drop else swap >r 1- recurse r> swap then
     ;
 [then]