diff --git a/cps/comic.py b/cps/comic.py
index 05ffef9b..91cb325d 100644
--- a/cps/comic.py
+++ b/cps/comic.py
@@ -24,21 +24,34 @@ import uploader
 
 
 def extractCover(tmp_file_name, original_file_extension):
+    cover_data = None
     if original_file_extension.upper() == '.CBZ':
         cf = zipfile.ZipFile(tmp_file_name)
-        compressed_name = cf.namelist()[0]
-        cover_data = cf.read(compressed_name)
+        for name in cf.namelist():
+            ext = os.path.splitext(name)
+            if len(ext) > 1:
+                extension = ext[1].lower()
+                if extension == '.jpg':
+                    cover_data = cf.read(name)
+                    break
     elif original_file_extension.upper() == '.CBT':
         cf = tarfile.TarFile(tmp_file_name)
-        compressed_name = cf.getnames()[0]
-        cover_data = cf.extractfile(compressed_name).read()
+        for name in cf.getnames():
+            ext = os.path.splitext(name)
+            if len(ext) > 1:
+                extension = ext[1].lower()
+                if extension == '.jpg':
+                    cover_data = cf.extractfile(name).read()
+                    break
 
     prefix = os.path.dirname(tmp_file_name)
-
-    tmp_cover_name = prefix + '/cover' + os.path.splitext(compressed_name)[1]
-    image = open(tmp_cover_name, 'wb')
-    image.write(cover_data)
-    image.close()
+    if cover_data:
+        tmp_cover_name = prefix + '/cover' + extension
+        image = open(tmp_cover_name, 'wb')
+        image.write(cover_data)
+        image.close()
+    else:
+        tmp_cover_name = None
     return tmp_cover_name
 
 
diff --git a/cps/static/js/kthoom.js b/cps/static/js/kthoom.js
index 6a107b9a..6ab25ad7 100644
--- a/cps/static/js/kthoom.js
+++ b/cps/static/js/kthoom.js
@@ -99,14 +99,15 @@ kthoom.setSettings = function() {
 };
 
 var createURLFromArray = function(array, mimeType) {
-    var offset = array.byteOffset, len = array.byteLength;
+    var offset = array.byteOffset;
+    var len = array.byteLength;
     var url;
     var blob;
 
     if (mimeType === 'image/xml+svg') {
         const xmlStr = new TextDecoder('utf-8').decode(array);
         return 'data:image/svg+xml;UTF-8,' + encodeURIComponent(xmlStr);
-  }
+    }
 
     // TODO: Move all this browser support testing to a common place
     //     and do it just once.
@@ -137,11 +138,13 @@ var createURLFromArray = function(array, mimeType) {
 kthoom.ImageFile = function(file) {
     this.filename = file.filename;
     var fileExtension = file.filename.split(".").pop().toLowerCase();
-    var mimeType = fileExtension === "png" ? "image/png" :
+    this.mimeType = fileExtension === "png" ? "image/png" :
         (fileExtension === "jpg" || fileExtension === "jpeg") ? "image/jpeg" :
             fileExtension === "gif" ? "image/gif" : fileExtension == 'svg' ? 'image/xml+svg' : undefined;
-    this.dataURI = createURLFromArray(file.fileData, mimeType);
-    this.data = file;
+    if ( this.mimeType !== undefined) {
+        this.dataURI = createURLFromArray(file.fileData, this.mimeType);
+        this.data = file;
+    }
 };
 
 
@@ -169,34 +172,42 @@ function loadFromArrayBuffer(ab) {
         unarchiver.addEventListener(bitjs.archive.UnarchiveEvent.Type.PROGRESS,
             function(e) {
                 var percentage = e.currentBytesUnarchived / e.totalUncompressedBytesInArchive;
-                totalImages = e.totalFilesInArchive;
+                if (totalImages === 0) {
+                    totalImages = e.totalFilesInArchive;
+                }
                 updateProgress(percentage *100);
                 lastCompletion = percentage * 100;
             });
         unarchiver.addEventListener(bitjs.archive.UnarchiveEvent.Type.EXTRACT,
             function(e) {
-            // convert DecompressedFile into a bunch of ImageFiles
+                // convert DecompressedFile into a bunch of ImageFiles
                 if (e.unarchivedFile) {
                     var f = e.unarchivedFile;
                     // add any new pages based on the filename
                     if (imageFilenames.indexOf(f.filename) === -1) {
-                        imageFilenames.push(f.filename);
-                        imageFiles.push(new kthoom.ImageFile(f));
-        				// add thumbnails to the TOC list
-        				$("#thumbnails").append(
-            				"<li>" +
-                				"<a data-page='" + imageFiles.length + "'>" +
-                    				"<img src='" + imageFiles[imageFiles.length - 1].dataURI + "'/>" +
-                    				"<span>" + imageFiles.length + "</span>" +
-                				"</a>" +
-            				"</li>"
-        				);
+                        var test = new kthoom.ImageFile(f);
+                        if ( test.mimeType !== undefined) {
+                            imageFilenames.push(f.filename);
+                            imageFiles.push(test);
+                            // add thumbnails to the TOC list
+                            $("#thumbnails").append(
+                                "<li>" +
+                                    "<a data-page='" + imageFiles.length + "'>" +
+                                        "<img src='" + imageFiles[imageFiles.length - 1].dataURI + "'/>" +
+                                        "<span>" + imageFiles.length + "</span>" +
+                                    "</a>" +
+                                "</li>"
+                            );
+                            // display first page if we haven't yet
+                            if (imageFiles.length === currentImage + 1) {
+                                updatePage(lastCompletion);
+                            }
+                        }
+                        else {
+                            totalImages--;
+                        }
                     }
                 }
-                // display first page if we haven't yet
-                if (imageFiles.length === currentImage + 1) {
-                    updatePage(lastCompletion);
-                }
             });
         unarchiver.addEventListener(bitjs.archive.UnarchiveEvent.Type.FINISH,
             function() {
diff --git a/cps/static/js/unzip.js b/cps/static/js/unzip.js
index f0370f53..0a067516 100644
--- a/cps/static/js/unzip.js
+++ b/cps/static/js/unzip.js
@@ -113,6 +113,7 @@ ZipLocalFile.prototype.unzip = function() {
         info("ZIP v" + this.version + ", store only: " + this.filename + " (" + this.compressedSize + " bytes)");
         currentBytesUnarchivedInFile = this.compressedSize;
         currentBytesUnarchived += this.compressedSize;
+        this.fileData = zeroCompression(this.fileData, this.uncompressedSize);
     }
     // version == 20, compression method == 8 (DEFLATE)
     else if (this.compressionMethod == 8) {
@@ -493,6 +494,16 @@ function inflateBlockData(bstream, hcLiteralTable, hcDistanceTable, buffer) {
     return blockSize;
 }
 
+function zeroCompression(compressedData, numDecompressedBytes) {
+    var bstream = new bitjs.io.BitStream(compressedData.buffer,
+        false /* rtl */,
+        compressedData.byteOffset,
+        compressedData.byteLength);
+    var buffer = new bitjs.io.ByteBuffer(numDecompressedBytes);
+    buffer.insertBytes(bstream.readBytes(numDecompressedBytes));
+    return buffer.data;
+}
+
 // {Uint8Array} compressedData A Uint8Array of the compressed file data.
 // compression method 8
 // deflate: http://tools.ietf.org/html/rfc1951
diff --git a/cps/static/js/uploadprogress.js b/cps/static/js/uploadprogress.js
index 1711f182..eef5f853 100644
--- a/cps/static/js/uploadprogress.js
+++ b/cps/static/js/uploadprogress.js
@@ -170,7 +170,7 @@
         replaceForm: function(html) {
             var newForm;
             var formId = this.$form.attr("id");
-            if ( typeof(formId) !== "undefined") {
+            if ( typeof formId !== "undefined") {
                 newForm = $(html).find("#" + formId);
             } else {
                 newForm = $(html).find("form");