diff --git a/index.html b/index.html
index 9cb124f..759bb70 100644
--- a/index.html
+++ b/index.html
@@ -529,6 +529,13 @@
 								<hr>
 
 
+								<label>Replace By Fee (RBF)</label>
+								<p class="checkbox">
+									<label><input type="checkbox" id="txRBF" class="checkbox-inline"> Make this a <a href="https://en.bitcoin.it/wiki/Transaction_replacement" target="_blank">RBF transaction</a>.</label>
+								</p>
+
+								<hr>
+
 								<label>Network</label>
 								<p>The <a href="#settings">settings</a> page can be used to select alternative networks of which you can retrieve your unspent outputs and broadcast a signed transaction into.</p>
 
@@ -724,6 +731,7 @@
 							<div><b>Version</b>: <span class="transactionVersion"></span></div>
 							<div><b>Transaction Size</b>: <span class="transactionSize"></span></div>
 							<div><b>Lock time</b>: <span class="transactionLockTime"></span></div>
+							<div class="transactionRBF"><b>RBF</b>: This is a <a href="https://en.bitcoin.it/wiki/Transaction_replacement">replace by fee</a> transaction!</div>
 
 							<hr>
 
diff --git a/js/coin.js b/js/coin.js
index 35ff63b..c7b2efb 100644
--- a/js/coin.js
+++ b/js/coin.js
@@ -776,11 +776,11 @@
 		r.block = null;
 
 		/* add an input to a transaction */
-		r.addinput = function(txid, index, script){
+		r.addinput = function(txid, index, script, sequence){
 			var o = {};
 			o.outpoint = {'hash':txid, 'index':index};
 			o.script = coinjs.script(script||[]);
-			o.sequence = (r.lock_time==0) ? 4294967295 : 0;
+			o.sequence = sequence || ((r.lock_time==0) ? 4294967295 : 0);
 			return this.ins.push(o);
 		}
 
diff --git a/js/coinbin.js b/js/coinbin.js
index 7153734..c61cdea 100644
--- a/js/coinbin.js
+++ b/js/coinbin.js
@@ -487,7 +487,12 @@ $(document).ready(function() {
 			}
 
 			if(!$(o).hasClass("has-error")){
-				tx.addinput($(".txId",o).val(), $(".txIdN",o).val(), $(".txIdScript",o).val());
+				var seq = null;
+				if($("#txRBF").is(":checked")){
+					seq = 0xffffffff-2;
+				}
+
+				tx.addinput($(".txId",o).val(), $(".txIdN",o).val(), $(".txIdScript",o).val(), seq);
 			} else {
 				$('#putTabs a[href="#txinputs"]').attr('style','color:#a94442;');
 			}
@@ -1087,6 +1092,7 @@ $(document).ready(function() {
 			$("#verifyTransactionData .transactionVersion").html(decode['version']);
 			$("#verifyTransactionData .transactionSize").html(decode.size()+' <i>bytes</i>');
 			$("#verifyTransactionData .transactionLockTime").html(decode['lock_time']);
+			$("#verifyTransactionData .transactionRBF").hide();
 			$("#verifyTransactionData").removeClass("hidden");
 			$("#verifyTransactionData tbody").html("");
 
@@ -1112,6 +1118,11 @@ $(document).ready(function() {
 				}
 				h += '</td>';
 				h += '</tr>';
+
+				//debug
+				if(parseInt(o.sequence)<(0xFFFFFFFF-1)){
+					$("#verifyTransactionData .transactionRBF").show();
+				}
 			});
 
 			$(h).appendTo("#verifyTransactionData .ins tbody");
diff --git a/sha1sum b/sha1sum
index 1a5628c..a013f99 100644
--- a/sha1sum
+++ b/sha1sum
@@ -1,9 +1,9 @@
----- Version 1.2 2016.05.09 ----
+---- Version 1.2 2016.05.21 ----
 77e4519962e2f6a9fc93342137dbb31c33b76b04  ./js/aes.js
 3a09a8fc0cfe828b57fc798d668234d0490ee1a6  ./js/bootstrap-datetimepicker.min.js
 253711c6d825de55a8360552573be950da180614  ./js/bootstrap.min.js
-ca3f654f247fef67de2cf6e01c3aa80db1812e5d  ./js/coin.js
-5f9639a17f1ba88e06a48cccd2b4b1f970bdf2e2  ./js/coinbin.js
+47f489ba671aba4ca3919ac6d966c65956d562c7  ./js/coinbin.js
+1bb89d9fc4147b53a963009af3e28d7928497947  ./js/coin.js
 988565bc2cb402d63ed5c5fd7ff47c4278efc2c5  ./js/collapse.js
 9ba5ede3d7f9d4c8fd623395f196adfdcf7e970f  ./js/crypto-min.js
 f7c09f2f5a721371e7d478050119f7e2d58e3ef9  ./js/crypto-sha256-hmac.js
@@ -30,4 +30,4 @@ de51a8494180a6db074af2dee2383f0a363c5b08  ./fonts/glyphicons-halflings-regular.s
 278e49a86e634da6f2a02f3b47dd9d2a8f26210f  ./fonts/glyphicons-halflings-regular.woff
 44bc1850f570972267b169ae18f1cb06b611ffa2  ./fonts/glyphicons-halflings-regular.ttf
 48ff08f459ff55ae54e594b4ae307d1d8e6f74b3  ./README.md
-05bc991db2105acda4333792582f5350012a0129  ./index.html
+52a93441529216ddce10d7f653e462ec06e058b9  ./index.html