diff --git a/nimbus/vm/computation.nim b/nimbus/vm/computation.nim
index c96f64ba4..16d95e8d1 100644
--- a/nimbus/vm/computation.nim
+++ b/nimbus/vm/computation.nim
@@ -235,7 +235,7 @@ proc writeContract*(c: Computation, fork: Fork): bool {.gcsafe.} =
     debug "Contract code size exceeds EIP170", limit=EIP170_CODE_SIZE_LIMIT, actual=contractCode.len
     return false
 
-  if fork >= FkLondon and contractCode[0] == 0xFE.byte:
+  if fork >= FkLondon and contractCode[0] == 0xEF.byte:
     debug "Contract code can't start with 0xEF byte"
     return false
 
diff --git a/nimbus/vm2/computation.nim b/nimbus/vm2/computation.nim
index 3361081b7..302de4637 100644
--- a/nimbus/vm2/computation.nim
+++ b/nimbus/vm2/computation.nim
@@ -175,7 +175,7 @@ proc writeContract*(c: Computation, fork: Fork): bool {.gcsafe.} =
       actual = contractCode.len
     return false
 
-  if fork >= FkLondon and contractCode[0] == 0xFE.byte:
+  if fork >= FkLondon and contractCode[0] == 0xEF.byte:
     debug "Contract code can't start with 0xEF byte"
     return false