diff --git a/std/string/array/duplicate.lb b/std/string/array/duplicate.lb
new file mode 100644
index 0000000..c979ca4
--- /dev/null
+++ b/std/string/array/duplicate.lb
@@ -0,0 +1,52 @@
+@ 0
+ args 0
+ size
+ #exec std/string/array/rev.lb
+ |#insert push
+ #insert swap
+ #insert |jmp
+ size
+
+; |
+; 'T
+; 'e
+; 's
+; 't
+; 4
+; >
+
+
+; |size string[size]> (size)
+ push 0
+@ 1
+; |index...> (size)
+
+ dup
+
+ push 2
+ jmp 255
+ @ 2
+ 
+; |size index index...> (size)
+ sub
+ jz 254
+
+; |index...> (size)
+
+ push 3
+ jmp 255
+ @ 3
+
+ #expr +
+; |size-1 index...>
+ pick
+
+ swap
+ 
+ #expr +
+ jmp 1
+
+@ 254
+ quit
+
+@ 255