diff --git a/js/canvas-to-blob.js b/js/canvas-to-blob.js
index d35ce0a..8b8cc76 100644
--- a/js/canvas-to-blob.js
+++ b/js/canvas-to-blob.js
@@ -36,20 +36,33 @@
             }()),
         BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder ||
             window.MozBlobBuilder || window.MSBlobBuilder,
+        dataURIPattern = /^data:((.*?)(;charset=.*?)?)(;base64)?,/,
         dataURLtoBlob = (hasBlobConstructor || BlobBuilder) && window.atob &&
             window.ArrayBuffer && window.Uint8Array && function (dataURI) {
-                var byteString,
+                var matches,
+                    mediaType,
+                    isBase64,
+                    dataString,
+                    byteString,
                     arrayBuffer,
                     intArray,
                     i,
-                    mimeString,
                     bb;
-                if (dataURI.split(',')[0].indexOf('base64') >= 0) {
+                // Parse the dataURI components as per RFC 2397
+                matches = dataURI.match(dataURIPattern);
+                if (!matches) throw new Error('invalid data URI');
+                // Default to text/plain;charset=US-ASCII
+                mediaType = matches[2] ?
+                    matches[1] :
+                    'text/plain' + (matches[3] || ';charset=US-ASCII');
+                isBase64 = !!matches[4];
+                dataString = dataURI.slice(matches[0].length);
+                if (isBase64) {
                     // Convert base64 to raw binary data held in a string:
-                    byteString = atob(dataURI.split(',')[1]);
+                    byteString = atob(dataString);
                 } else {
                     // Convert base64/URLEncoded data component to raw binary data:
-                    byteString = decodeURIComponent(dataURI.split(',')[1]);
+                    byteString = decodeURIComponent(dataString);
                 }
                 // Write the bytes of the string to an ArrayBuffer:
                 arrayBuffer = new ArrayBuffer(byteString.length);
@@ -57,18 +70,16 @@
                 for (i = 0; i < byteString.length; i += 1) {
                     intArray[i] = byteString.charCodeAt(i);
                 }
-                // Separate out the mime component:
-                mimeString = dataURI.split(',')[0].split(':')[1].split(';')[0];
                 // Write the ArrayBuffer (or ArrayBufferView) to a blob:
                 if (hasBlobConstructor) {
                     return new Blob(
                         [hasArrayBufferViewSupport ? intArray : arrayBuffer],
-                        {type: mimeString}
+                        {type: mediaType}
                     );
                 }
                 bb = new BlobBuilder();
                 bb.append(arrayBuffer);
-                return bb.getBlob(mimeString);
+                return bb.getBlob(mediaType);
             };
     if (window.HTMLCanvasElement && !CanvasPrototype.toBlob) {
         if (CanvasPrototype.mozGetAsFile) {
diff --git a/js/canvas-to-blob.min.js b/js/canvas-to-blob.min.js
index 3a02a8a..90372f8 100644
--- a/js/canvas-to-blob.min.js
+++ b/js/canvas-to-blob.min.js
@@ -1 +1 @@
-!function(a){"use strict";var b=a.HTMLCanvasElement&&a.HTMLCanvasElement.prototype,c=a.Blob&&function(){try{return Boolean(new Blob)}catch(a){return!1}}(),d=c&&a.Uint8Array&&function(){try{return 100===new Blob([new Uint8Array(100)]).size}catch(a){return!1}}(),e=a.BlobBuilder||a.WebKitBlobBuilder||a.MozBlobBuilder||a.MSBlobBuilder,f=(c||e)&&a.atob&&a.ArrayBuffer&&a.Uint8Array&&function(a){var b,f,g,h,i,j;for(b=a.split(",")[0].indexOf("base64")>=0?atob(a.split(",")[1]):decodeURIComponent(a.split(",")[1]),f=new ArrayBuffer(b.length),g=new Uint8Array(f),h=0;h<b.length;h+=1)g[h]=b.charCodeAt(h);return i=a.split(",")[0].split(":")[1].split(";")[0],c?new Blob([d?g:f],{type:i}):(j=new e,j.append(f),j.getBlob(i))};a.HTMLCanvasElement&&!b.toBlob&&(b.mozGetAsFile?b.toBlob=function(a,c,d){a(d&&b.toDataURL&&f?f(this.toDataURL(c,d)):this.mozGetAsFile("blob",c))}:b.toDataURL&&f&&(b.toBlob=function(a,b,c){a(f(this.toDataURL(b,c)))})),"function"==typeof define&&define.amd?define(function(){return f}):a.dataURLtoBlob=f}(window);
\ No newline at end of file
+!function(a){"use strict";var b=a.HTMLCanvasElement&&a.HTMLCanvasElement.prototype,c=a.Blob&&function(){try{return Boolean(new Blob)}catch(a){return!1}}(),d=c&&a.Uint8Array&&function(){try{return 100===new Blob([new Uint8Array(100)]).size}catch(a){return!1}}(),e=a.BlobBuilder||a.WebKitBlobBuilder||a.MozBlobBuilder||a.MSBlobBuilder,f=/^data:((.*?)(;charset=.*?)?)(;base64)?,/,g=(c||e)&&a.atob&&a.ArrayBuffer&&a.Uint8Array&&function(a){var b,g,h,i,j,k,l,m,n;if(b=a.match(f),!b)throw new Error("invalid data URI");for(g=b[2]?b[1]:"text/plain"+(b[3]||";charset=US-ASCII"),h=!!b[4],i=a.slice(b[0].length),j=h?atob(i):decodeURIComponent(i),k=new ArrayBuffer(j.length),l=new Uint8Array(k),m=0;m<j.length;m+=1)l[m]=j.charCodeAt(m);return c?new Blob([d?l:k],{type:g}):(n=new e,n.append(k),n.getBlob(g))};a.HTMLCanvasElement&&!b.toBlob&&(b.mozGetAsFile?b.toBlob=function(a,c,d){a(d&&b.toDataURL&&g?g(this.toDataURL(c,d)):this.mozGetAsFile("blob",c))}:b.toDataURL&&g&&(b.toBlob=function(a,b,c){a(g(this.toDataURL(b,c)))})),"function"==typeof define&&define.amd?define(function(){return g}):a.dataURLtoBlob=g}(window);
\ No newline at end of file