diff --git a/src/calibre/devices/mtp/unix/driver.py b/src/calibre/devices/mtp/unix/driver.py
index c763da3a45..71914cddc0 100644
--- a/src/calibre/devices/mtp/unix/driver.py
+++ b/src/calibre/devices/mtp/unix/driver.py
@@ -25,6 +25,8 @@ def fingerprint(d):
     return MTPDevice(d.busnum, d.devnum, d.vendor_id, d.product_id, d.bcd,
             d.serial, d.manufacturer, d.product)
 
+APPLE = 0x05ac
+
 class MTP_DEVICE(MTPDeviceBase):
 
     # libusb(x) does not work on OS X. So no MTP support for OS X
@@ -53,7 +55,8 @@ class MTP_DEVICE(MTPDeviceBase):
         devs = set()
         for d in devices_on_system:
             fp = fingerprint(d)
-            if fp not in self.blacklisted_devices:
+            if fp not in self.blacklisted_devices and fp.vendor_id != APPLE:
+                # Do not try to open Apple devices
                 devs.add(fp)
 
         # Clean up ejected devices
@@ -93,7 +96,7 @@ class MTP_DEVICE(MTPDeviceBase):
             p(err)
             return False
         devs = [d for d in devices_on_system if (d.vendor_id, d.product_id)
-                in self.known_devices]
+                in self.known_devices and d.vendor_id != APPLE]
         if not devs:
             p('No known MTP devices connected to system')
             return False
diff --git a/src/calibre/ebooks/mobi/reader/markup.py b/src/calibre/ebooks/mobi/reader/markup.py
index 161a76f284..73ba09a189 100644
--- a/src/calibre/ebooks/mobi/reader/markup.py
+++ b/src/calibre/ebooks/mobi/reader/markup.py
@@ -42,8 +42,8 @@ def update_internal_links(mobi8_reader):
                             mr.header.codec) + suffix
                     tag = posfid_index_pattern.sub(replacement, tag, 1)
                 srcpieces[j] = tag
-        part = ''.join([x.decode(mr.header.codec) for x in srcpieces])
-        parts.append(part)
+        raw = b''.join(srcpieces)
+        parts.append(raw.decode(mr.header.codec))
 
     # All parts are now unicode and have no internal links
     return parts
diff --git a/src/calibre/ebooks/mobi/writer8/skeleton.py b/src/calibre/ebooks/mobi/writer8/skeleton.py
index 2c3562e87b..c22d8342a6 100644
--- a/src/calibre/ebooks/mobi/writer8/skeleton.py
+++ b/src/calibre/ebooks/mobi/writer8/skeleton.py
@@ -305,7 +305,7 @@ class Chunker(object):
         ans.append(start)
         while rest:
             start, rest = split_multibyte_text(rest)
-            ans.append(b'<span class="AmznBigTextBlock">' + start + '</span>')
+            ans.append(b'<span class="AmznBigTextBlock">' + start + b'</span>')
         return [Chunk(x, self.chunk_selector) for x in ans]
 
     def merge_small_chunks(self, chunks):