diff --git a/lib/script/opcode.js b/lib/script/opcode.js
index 98c41b1b..57b98e9b 100644
--- a/lib/script/opcode.js
+++ b/lib/script/opcode.js
@@ -416,7 +416,7 @@ Opcode.fromSymbol = function fromSymbol(name) {
     name = name.toUpperCase();
 
   if (!util.startsWith(name, 'OP_'))
-    name = 'OP_' + name;
+    name = `OP_${name}`;
 
   op = common.opcodes[name];
   assert(op != null, 'Unknown opcode.');
diff --git a/lib/script/script.js b/lib/script/script.js
index 6d960970..6cf5853b 100644
--- a/lib/script/script.js
+++ b/lib/script/script.js
@@ -2721,7 +2721,7 @@ Script.prototype.fromString = function fromString(code) {
       symbol = symbol.toUpperCase();
 
     if (!util.startsWith(symbol, 'OP_'))
-      symbol = 'OP_' + symbol;
+      symbol = `OP_${symbol}`;
 
     if (opcodes[symbol] == null) {
       if (op[0] === '\'') {