diff --git a/lib/bcoin/script.js b/lib/bcoin/script.js
index 0ad7d1b5..bf842558 100644
--- a/lib/bcoin/script.js
+++ b/lib/bcoin/script.js
@@ -2476,7 +2476,7 @@ Script.isCode = function isCode(raw) {
     if (op.value === -1)
       return false;
 
-    if (constants.opcodesByVal[op.value] == null)
+    if (op.value > opcodes.OP_NOP10)
       return false;
   }