diff --git a/src/evm/instructions.rs b/src/evm/instructions.rs
index 5d61d3f39..d30c4ed3a 100644
--- a/src/evm/instructions.rs
+++ b/src/evm/instructions.rs
@@ -25,9 +25,9 @@ pub fn get_dup_position (i: Instruction) -> usize {
 
 #[test]
 fn test_get_dup_position() {
-	assert_eq!(get_dup_position(DUP1), 1);
-	assert_eq!(get_dup_position(DUP5), 5);
-	assert_eq!(get_dup_position(DUP10), 10);
+	assert_eq!(get_dup_position(DUP1), 0);
+	assert_eq!(get_dup_position(DUP5), 4);
+	assert_eq!(get_dup_position(DUP10), 9);
 }
 
 pub fn get_swap_position (i : Instruction) -> usize {