diff --git a/RomPatcher.js b/RomPatcher.js
index 3d47f90..c085f2a 100644
--- a/RomPatcher.js
+++ b/RomPatcher.js
@@ -1,6 +1,16 @@
-/* RomPatcher.js v20171102 - Marc Robledo 2016-2017 - http://www.marcrobledo.com/license */
-var MAX_ROM_SIZE=33554432;
-var romFile, patch, romFile1, romFile2, tempFile, romHashes={};
+/* RomPatcher.js v20171107 - Marc Robledo 2016-2017 - http://www.marcrobledo.com/license */
+var MAX_ROM_SIZE=33554432;var SNES_HEADERED_ROMS_SIZE=[
+	262144+512,
+	524288+512,
+	1048576+512,
+	2097152+512,
+	4194304+512,
+	8388608+512,
+	16777216+512,
+	33554432+512,
+	50331648+512
+];
+var romFile, headeredRomFile, unheaderedRomFile, patch, romFile1, romFile2, tempFile;
 /* Shortcuts */
 function addEvent(e,ev,f){e.addEventListener(ev,f,false)}
 function el(e){return document.getElementById(e)}
@@ -17,16 +27,16 @@ addEvent(window,'load',function(){
 
 	addEvent(el('input-file-rom'), 'change', function(){
 		romFile=new MarcBinFile(this, function(){
-			el('rom-info').innerHTML='';
-			sha1(romFile);
-			romHashes.crc32=crc32(romFile);
-			romHashes.md5=md5(romFile);
+			el('checkbox-removeheader').checked=false;
+			unheaderedRomFile=null;
 
-			var crc32str=romHashes.crc32.toString(16);
-			while(crc32str.length<8)
-				crc32str='0'+crc32str;
-			el('rom-info').innerHTML+='CRC32: '+crc32str+'<br/>';
-			el('rom-info').innerHTML+='MD5:   '+romHashes.md5+'<br/>';
+			if(SNES_HEADERED_ROMS_SIZE.indexOf(romFile.fileSize)>=0){
+				el('row-removeheader').style.display='flex';
+			}else{
+				el('row-removeheader').style.display='none';
+			}
+	
+			updateChecksums(romFile);
 		});
 	});
 	addEvent(el('input-file-patch'), 'change', function(){
@@ -38,10 +48,36 @@ addEvent(window,'load',function(){
 	addEvent(el('input-file-rom2'), 'change', function(){
 		romFile2=new MarcBinFile(this);
 	});
+
+	addEvent(el('checkbox-removeheader'), 'change', function(){
+		if(!unheaderedRomFile){
+			headeredRomFile=romFile;
+			unheaderedRomFile=new MarcBinFile(headeredRomFile.fileSize-512);
+			unheaderedRomFile.writeBytes(0, headeredRomFile.readBytes(512, headeredRomFile.fileSize-512));
+			unheaderedRomFile.fileName=headeredRomFile.fileName;
+		}
+
+		if(this.checked)
+			romFile=unheaderedRomFile;
+		else
+			romFile=headeredRomFile;
+
+
+		updateChecksums(romFile);
+	});
 });
 
 
+function updateChecksums(file){
+	el('rom-info').style.display='block';
+	sha1(file);
 
+	var crc32str=crc32(file).toString(16);
+	while(crc32str.length<8)
+		crc32str='0'+crc32str;
+	el('crc32').innerHTML=crc32str;
+	el('md5').innerHTML=md5(file);
+}
 
 
 
@@ -130,8 +166,7 @@ function sha1(file){
 					hexString+='0'+bytes[i].toString(16);
 				else
 					hexString+=bytes[i].toString(16);
-			romHashes.sha1=hexString;
-			el('rom-info').innerHTML+='SHA-1: '+romHashes.sha1+'<br/>';
+			el('sha1').innerHTML=hexString;
 		}).catch(function(error){
 			console.error(error);
 		});
diff --git a/aps.js b/aps.js
index 70b58b0..099e3b9 100644
--- a/aps.js
+++ b/aps.js
@@ -1,4 +1,4 @@
-/* APS (N64) module for RomPatcher.js v20170723 - Marc Robledo 2017 - http://www.marcrobledo.com/license */
+/* APS (N64) module for RomPatcher.js v20171112 - Marc Robledo 2017 - http://www.marcrobledo.com/license */
 /* File format specification: https://github.com/btimofeev/UniPatcher/wiki/APS-(N64) */
 
 var RECORD_RLE=0x0000;
@@ -90,7 +90,7 @@ APS.prototype.export=function(){
 APS.prototype.apply=function(romFile){
 	if(this.headerType===1){
 		if(romFile.readString(0x3c, 3)!==this.header.cartId){
-			MarcDialogs.alert('Invalid ROM cart id');
+			MarcDialogs.alert('Error: invalid ROM cart id');
 			return false;
 		}
 		var crc=romFile.readBytes(0x10, 8);
@@ -100,7 +100,7 @@ APS.prototype.apply=function(romFile){
 				crcOk=false;
 		}
 		if(!crcOk){
-			MarcDialogs.alert('Invalid ROM checksum');
+			MarcDialogs.alert('Error: invalid ROM checksum');
 			return false;
 		}
 	}
diff --git a/bps.js b/bps.js
index 0522b5c..1c1f9d0 100644
--- a/bps.js
+++ b/bps.js
@@ -1,4 +1,4 @@
-/* BPS module for RomPatcher.js v20171103	 - Marc Robledo 2016-2017 - http://www.marcrobledo.com/license */
+/* BPS module for RomPatcher.js v20171112	 - Marc Robledo 2016-2017 - http://www.marcrobledo.com/license */
 /* File format specification: https://www.romhacking.net/documents/746/ */
 
 var BPS_MAGIC='BPS1';
@@ -30,7 +30,8 @@ BPS.prototype.toString=function(){
 }*/
 BPS.prototype.apply=function(romFile){
 	if(this.sourceChecksum!==crc32(romFile,false)){
-		MarcDialogs.alert('Warning: invalid source ROM checksum');
+		MarcDialogs.alert('Error: invalid source ROM checksum');
+		return false;
 	}
 	
 	
diff --git a/index.html b/index.html
index c882ef6..c5b55ff 100644
--- a/index.html
+++ b/index.html
@@ -43,7 +43,17 @@
 			<div class="six columns text-right"><label for="input-file-rom">ROM file:</label></div>
 			<div class="six columns">
 				<input type="file" id="input-file-rom" />
-				<div id="rom-info" class="mono" style="font-size:12px"></div>
+				<div id="rom-info" class="mono" style="display:none;font-size:12px">
+					CRC32: <span id="crc32"></span><br/>
+					MD5: <span id="md5"></span><br/>
+					SHA-1: <span id="sha1"></span><br/>
+				</div>
+			</div>
+		</div>
+		<div class="row" id="row-removeheader" style="display:none">
+			<div class="six columns text-right"><label for="checkbox-removeheader">Remove header:</label></div>
+			<div class="six columns">
+				<input type="checkbox" id="checkbox-removeheader" />
 			</div>
 		</div>
 
diff --git a/manifest.appcache b/manifest.appcache
index 6f76606..b30dc20 100644
--- a/manifest.appcache
+++ b/manifest.appcache
@@ -1,5 +1,5 @@
 CACHE MANIFEST
-#v20171103
+#v20171112
 #CACHE:
 index.html
 RomPatcher.css
diff --git a/ups.js b/ups.js
index d228852..1b6ab66 100644
--- a/ups.js
+++ b/ups.js
@@ -1,4 +1,4 @@
-/* UPS module for RomPatcher.js v20170723 - Marc Robledo 2017 - http://www.marcrobledo.com/license */
+/* UPS module for RomPatcher.js v20171112 - Marc Robledo 2017 - http://www.marcrobledo.com/license */
 /* File format specification: http://www.romhacking.net/documents/392/ */
 
 var UPS_MAGIC='UPS1';
@@ -62,7 +62,7 @@ UPS.prototype.export=function(){
 }
 UPS.prototype.apply=function(romFile){
 	if(crc32(romFile)!==this.checksumInput){
-		MarcDialogs.alert('Invalid input ROM');
+		MarcDialogs.alert('Error: invalid input ROM checksum');
 		return false;
 	}
 
@@ -83,8 +83,7 @@ UPS.prototype.apply=function(romFile){
 	}
 
 	if(crc32(tempFile)!==this.checksumOutput){
-		MarcDialogs.alert('Invalid output ROM');
-		return false;
+		MarcDialogs.alert('Warning: invalid output ROM checksum');
 	}
 
 	return tempFile
@@ -159,7 +158,7 @@ function readUPSFile(file){
 	patchFile.checksumOutput=tempFile.readInt(seek+4);
 
 	if(tempFile.readInt(seek+8)!==crc32(file, true)){
-		MarcDialogs.alert('Invalid patch checksum');
+		MarcDialogs.alert('Warning: invalid patch checksum');
 	}
 	return patchFile;
 }