diff --git a/txscript/data/script_valid.json b/txscript/data/script_valid.json
index 064dde84..0dd9d217 100644
--- a/txscript/data/script_valid.json
+++ b/txscript/data/script_valid.json
@@ -80,6 +80,7 @@
 
 ["0 IFDUP", "DEPTH 1 EQUALVERIFY 0 EQUAL", "P2SH,STRICTENC"],
 ["1 IFDUP", "DEPTH 2 EQUALVERIFY 1 EQUALVERIFY 1 EQUAL", "P2SH,STRICTENC"],
+["0x05 0x0100000000 IFDUP", "DEPTH 2 EQUALVERIFY 0x05 0x0100000000 EQUAL", "P2SH,STRICTENC", "IFDUP dups non ints"],
 ["0 DROP", "DEPTH 0 EQUAL", "P2SH,STRICTENC"],
 ["0", "DUP 1 ADD 1 EQUALVERIFY 0 EQUAL", "P2SH,STRICTENC"],
 ["0 1", "NIP", "P2SH,STRICTENC"],
diff --git a/txscript/opcode.go b/txscript/opcode.go
index 8245151b..7781465d 100644
--- a/txscript/opcode.go
+++ b/txscript/opcode.go
@@ -1084,14 +1084,14 @@ func opcode2Swap(op *parsedOpcode, vm *Engine) error {
 // Stack transformation (x1==0): [... x1] -> [...]
 // Stack transformation (x1!=0): [... x1] -> [... x1]
 func opcodeIfDup(op *parsedOpcode, vm *Engine) error {
-	val, err := vm.dstack.PeekInt(0)
+	so, err := vm.dstack.PeekByteArray(0)
 	if err != nil {
 		return err
 	}
 
 	// Push copy of data iff it isn't zero
-	if val != 0 {
-		vm.dstack.PushInt(val)
+	if asBool(so) {
+		vm.dstack.PushByteArray(so)
 	}
 
 	return nil