diff --git a/lib/bcoin/tx.js b/lib/bcoin/tx.js
index 04c540d0..e720cbb8 100644
--- a/lib/bcoin/tx.js
+++ b/lib/bcoin/tx.js
@@ -194,16 +194,16 @@ TX.prototype.scriptInput = function scriptInput(index, pub, redeem) {
 
   if (bcoin.script.isPubkey(s)) {
     // P2PK
-    input.script = [ [] ];
+    input.script = [[]];
   } else if (bcoin.script.isPubkeyhash(s)) {
     // P2PKH
-    input.script = [ [], pub ];
+    input.script = [[], pub];
   } else if (bcoin.script.isMultisig(s)) {
     // Multisig
     // Technically we should create m signature slots,
     // but we create n signature slots so we can order
     // the signatures properly.
-    input.script = [ [] ];
+    input.script = [[]];
 
     // Grab `n` value (number of keys).
     n = s[s.length - 2];
@@ -213,10 +213,17 @@ TX.prototype.scriptInput = function scriptInput(index, pub, redeem) {
       input.script[i + 1] = [];
   } else {
     // Likely a non-standard scripthash multisig
-    // input. Just set up the empty array. Also,
-    // only allow nonstandard types for scripthash.
-    if (redeem)
-      input.script = [ [] ];
+    // input. Determine n value by counting keys.
+    // Also, only allow nonstandard types for
+    // scripthash.
+    if (redeem) {
+      input.script = [[]];
+      // Fill script with `n` signature slots.
+      for (i = 0; i < s.length; i++) {
+        if (bcoin.script.isKey(s[i]))
+          input.script.push([]);
+      }
+    }
   }
 
   // P2SH requires the redeem script after signatures
@@ -782,7 +789,7 @@ TX.prototype.isCoinbase = function isCoinbase() {
 
 TX.prototype.maxSize = function maxSize() {
   var copy = this.clone();
-  var i, input, total, size, s, m, n;
+  var i, j, input, total, size, s, m, n;
 
   // Create copy with 0-script inputs
   for (i = 0; i < copy.inputs.length; i++)
@@ -856,6 +863,12 @@ TX.prototype.maxSize = function maxSize() {
       size += 1;
       // OP_CHECKMULTISIG
       size += 1;
+    } else {
+      // OP_PUSHDATA0 [signature]
+      for (j = 0; j < s.length; j++) {
+        if (bcoin.script.isKey(s[j]))
+          size += 1 + 73;
+      }
     }
 
     // Byte for varint size of input script