diff --git a/src/calibre/devices/apple/driver.py b/src/calibre/devices/apple/driver.py
index 5a0496e863..aaa9382612 100644
--- a/src/calibre/devices/apple/driver.py
+++ b/src/calibre/devices/apple/driver.py
@@ -2517,28 +2517,25 @@ class ITUNES(DriverBase):
             opf = [x for x in fnames if '.opf' in x][0]
             if opf:
                 opf_tree = etree.fromstring(zf_opf.read(opf))
-                ns_map = opf_tree.nsmap.keys()
-                for item in ns_map:
-                    ns = opf_tree.nsmap[item]
-                    md_el = opf_tree.find(".//{%s}metadata" % ns)
-                    if md_el is not None:
-                        ts = md_el.find('.//{%s}meta[@name="calibre:timestamp"]')
-                        if ts:
-                            timestamp = ts.get('content')
-                            old_ts = parse_date(timestamp)
-                            metadata.timestamp = datetime.datetime(old_ts.year, old_ts.month, old_ts.day, old_ts.hour,
-                                                       old_ts.minute, old_ts.second, old_ts.microsecond+1, old_ts.tzinfo)
-                        else:
-                            metadata.timestamp = now()
-                            if DEBUG:
-                                self.log.info("   add timestamp: %s" % metadata.timestamp)
-                        break
+                md_els = opf_tree.xpath('.//*[local-name()="metadata"]')
+                if md_els:
+                    ts = md_els[0].find('.//*[@name="calibre:timestamp"]')
+                    if ts is not None:
+                        timestamp = ts.get('content')
+                        old_ts = parse_date(timestamp)
+                        metadata.timestamp = datetime.datetime(old_ts.year, old_ts.month, old_ts.day, old_ts.hour,
+                                                   old_ts.minute, old_ts.second, old_ts.microsecond+1, old_ts.tzinfo)
+                        if DEBUG:
+                            self.log.info("   existing timestamp: %s" % metadata.timestamp)
+                    else:
+                        metadata.timestamp = now()
+                        if DEBUG:
+                            self.log.info("   add timestamp: %s" % metadata.timestamp)
                 else:
                     metadata.timestamp = now()
                     if DEBUG:
                         self.log.warning("   missing <metadata> block in OPF file")
                         self.log.info("   add timestamp: %s" % metadata.timestamp)
-
                 # Force the language declaration for iBooks 1.1
                 #metadata.language = get_lang().replace('_', '-')