diff --git a/txscript/script.go b/txscript/script.go
index 2149dfe8..530a6ef6 100644
--- a/txscript/script.go
+++ b/txscript/script.go
@@ -134,6 +134,10 @@ var (
 )
 
 const (
+	// maxDataCarrierSize is the maximum number of bytes allowed in pushed
+	// data to be considered a nulldata transaction
+	maxDataCarrierSize = 80
+
 	// maxStackSize is the maximum combined height of stack and alt stack
 	// during execution.
 	maxStackSize = 1000
@@ -303,7 +307,8 @@ func isMultiSig(pops []parsedOpcode) bool {
 // false otherwise.
 func isNullData(pops []parsedOpcode) bool {
 	// A nulldata transaction is either a single OP_RETURN or an
-	// OP_RETURN SMALLDATA (where SMALLDATA is a push data up to 40 bytes).
+	// OP_RETURN SMALLDATA (where SMALLDATA is a push data up to
+	// maxDataCarrierSize bytes).
 	l := len(pops)
 	if l == 1 && pops[0].opcode.value == OP_RETURN {
 		return true
@@ -312,7 +317,7 @@ func isNullData(pops []parsedOpcode) bool {
 	return l == 2 &&
 		pops[0].opcode.value == OP_RETURN &&
 		pops[1].opcode.value <= OP_PUSHDATA4 &&
-		len(pops[1].data) <= 40
+		len(pops[1].data) <= maxDataCarrierSize
 }
 
 // isPushOnly returns true if the script only pushes data, false otherwise.
@@ -1728,7 +1733,6 @@ func CalcScriptInfo(sigscript, pkscript []byte, bip16 bool) (*ScriptInfo, error)
 
 		shInputs := expectedInputs(shPops, shClass)
 		if shInputs == -1 {
-			// We have no fucking clue, then.
 			si.ExpectedInputs = -1
 		} else {
 			si.ExpectedInputs += shInputs
diff --git a/txscript/script_test.go b/txscript/script_test.go
index 4c094ca9..904fa793 100644
--- a/txscript/script_test.go
+++ b/txscript/script_test.go
@@ -2263,7 +2263,12 @@ var scriptTypeTests = []scriptTypeTest{
 		script: []byte{
 			txscript.OP_RETURN,
 			txscript.OP_PUSHDATA1,
-			0x28, // 40
+			0x50, // 80
+			0x04, 0x67, 0x08, 0xaf, 0xdb, 0x0f, 0xe5, 0x54,
+			0x82, 0x71, 0x96, 0x7f, 0x1a, 0x67, 0x13, 0x0b,
+			0x71, 0x05, 0xcd, 0x6a, 0x82, 0x8e, 0x03, 0x90,
+			0x9a, 0x67, 0x96, 0x2e, 0x0e, 0xa1, 0xf6, 0x1d,
+			0xeb, 0x64, 0x9f, 0x6b, 0xc3, 0xf4, 0xce, 0xf3,
 			0x04, 0x67, 0x08, 0xaf, 0xdb, 0x0f, 0xe5, 0x54,
 			0x82, 0x71, 0x96, 0x7f, 0x1a, 0x67, 0x13, 0x0b,
 			0x71, 0x05, 0xcd, 0x6a, 0x82, 0x8e, 0x03, 0x90,
@@ -2278,7 +2283,12 @@ var scriptTypeTests = []scriptTypeTest{
 		script: []byte{
 			txscript.OP_RETURN,
 			txscript.OP_PUSHDATA1,
-			0x29, // 41
+			0x51, // 81
+			0x04, 0x67, 0x08, 0xaf, 0xdb, 0x0f, 0xe5, 0x54,
+			0x82, 0x71, 0x96, 0x7f, 0x1a, 0x67, 0x13, 0x0b,
+			0x71, 0x05, 0xcd, 0x6a, 0x82, 0x8e, 0x03, 0x90,
+			0x9a, 0x67, 0x96, 0x2e, 0x0e, 0xa1, 0xf6, 0x1d,
+			0xeb, 0x64, 0x9f, 0x6b, 0xc3, 0xf4, 0xce, 0xf3,
 			0x04, 0x67, 0x08, 0xaf, 0xdb, 0x0f, 0xe5, 0x54,
 			0x82, 0x71, 0x96, 0x7f, 0x1a, 0x67, 0x13, 0x0b,
 			0x71, 0x05, 0xcd, 0x6a, 0x82, 0x8e, 0x03, 0x90,