diff --git a/EIPS/eip-140.md b/EIPS/eip-140.md
index 1e205e5f..026e3025 100644
--- a/EIPS/eip-140.md
+++ b/EIPS/eip-140.md
@@ -22,7 +22,7 @@ Currently this is not possible. There are two practical ways to revert a transac
 
 ## Specification
 
-The `REVERT` instruction is introduced at `0xfd`. It expects two stack items, the top item is the `memory_offset` followed by `memory_length`. It does not produce any stack elements because it stops execution.
+On blocks with `block.number >= BYZANTIUM_FORK_BLKNUM`, the `REVERT` instruction is introduced at `0xfd`. It expects two stack items, the top item is the `memory_offset` followed by `memory_length`. It does not produce any stack elements because it stops execution.
 
 The semantics of `REVERT` with respect to memory and memory cost are identical to those of `RETURN`. The sequence of bytes given by `memory_offset` and `memory_length` is called "error message" in the following.
 
@@ -55,4 +55,4 @@ should:
 
 ## Copyright
 
-Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
\ No newline at end of file
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).