diff --git a/gui/qt/paytoedit.py b/gui/qt/paytoedit.py
index d13d80390..8adbfcaee 100644
--- a/gui/qt/paytoedit.py
+++ b/gui/qt/paytoedit.py
@@ -93,9 +93,11 @@ class PayToEdit(ScanQRTextEdit):
         for word in x.split():
             if word[0:3] == 'OP_':
                 assert word in opcodes.lookup
-                script += chr(opcodes.lookup[word])
+                opcode_int = opcodes.lookup[word]
+                assert opcode_int < 256  # opcode is single-byte
+                script += bitcoin.int_to_hex(opcode_int)
             else:
-                script += push_script(word).decode('hex')
+                script += push_script(word)
         return script
 
     def parse_amount(self, x):
diff --git a/lib/transaction.py b/lib/transaction.py
index aac770392..5fca0b8bc 100644
--- a/lib/transaction.py
+++ b/lib/transaction.py
@@ -229,10 +229,10 @@ opcodes = Enumeration("Opcodes", [
     "OP_WITHIN", "OP_RIPEMD160", "OP_SHA1", "OP_SHA256", "OP_HASH160",
     "OP_HASH256", "OP_CODESEPARATOR", "OP_CHECKSIG", "OP_CHECKSIGVERIFY", "OP_CHECKMULTISIG",
     "OP_CHECKMULTISIGVERIFY",
-    ("OP_SINGLEBYTE_END", 0xF0),
-    ("OP_DOUBLEBYTE_BEGIN", 0xF000),
-    "OP_PUBKEY", "OP_PUBKEYHASH",
-    ("OP_INVALIDOPCODE", 0xFFFF),
+    ("OP_NOP1", 0xB0),
+    ("OP_CHECKLOCKTIMEVERIFY", 0xB1), ("OP_CHECKSEQUENCEVERIFY", 0xB2),
+    "OP_NOP4", "OP_NOP5", "OP_NOP6", "OP_NOP7", "OP_NOP8", "OP_NOP9", "OP_NOP10",
+    ("OP_INVALIDOPCODE", 0xFF),
 ])
 
 
@@ -242,10 +242,6 @@ def script_GetOp(_bytes):
         vch = None
         opcode = _bytes[i]
         i += 1
-        if opcode >= opcodes.OP_SINGLEBYTE_END:
-            opcode <<= 8
-            opcode |= _bytes[i]
-            i += 1
 
         if opcode <= opcodes.OP_PUSHDATA4:
             nSize = opcode