diff --git a/src/calibre/gui2/dialogs/tweak_epub.ui b/src/calibre/gui2/dialogs/tweak_epub.ui
index ccd33f44ab..063460aaae 100644
--- a/src/calibre/gui2/dialogs/tweak_epub.ui
+++ b/src/calibre/gui2/dialogs/tweak_epub.ui
@@ -32,7 +32,7 @@
       <string>&amp;Explode ePub</string>
      </property>
      <property name="icon">
-      <iconset>
+      <iconset resource="../../../../resources/images.qrc">
        <normaloff>:/images/wizard.png</normaloff>:/images/wizard.png</iconset>
      </property>
     </widget>
@@ -49,7 +49,7 @@
       <string>&amp;Rebuild ePub</string>
      </property>
      <property name="icon">
-      <iconset>
+      <iconset resource="../../../../resources/images.qrc">
        <normaloff>:/images/exec.png</normaloff>:/images/exec.png</iconset>
      </property>
     </widget>
@@ -63,7 +63,7 @@
       <string>&amp;Cancel</string>
      </property>
      <property name="icon">
-      <iconset>
+      <iconset resource="../../../../resources/images.qrc">
        <normaloff>:/images/window-close.png</normaloff>:/images/window-close.png</iconset>
      </property>
     </widget>
@@ -71,7 +71,7 @@
    <item row="0" column="0">
     <widget class="QLabel" name="label">
      <property name="text">
-      <string>Explode the ePub to display contents in a file browser window. To tweak individual files, right-click, then 'Open with...' your editor of choice. When tweaks are complete, close the file browser window. Rebuild the ePub, updating your calibre library.</string>
+      <string>&lt;p&gt;Explode the ePub to display contents in a file browser window. To tweak individual files, right-click, then 'Open with...' your editor of choice. When tweaks are complete, close the file browser window &lt;b&gt;and the editor windows you used to edit files in the epub&lt;/b&gt;.&lt;/p&gt;&lt;p&gt;Rebuild the ePub, updating your calibre library.&lt;/p&gt;</string>
      </property>
      <property name="wordWrap">
       <bool>true</bool>
diff --git a/src/calibre/utils/zipfile.py b/src/calibre/utils/zipfile.py
index 8f22b5f9e2..dbcc125274 100644
--- a/src/calibre/utils/zipfile.py
+++ b/src/calibre/utils/zipfile.py
@@ -1147,28 +1147,27 @@ class ZipFile:
 
         self._writecheck(zinfo)
         self._didModify = True
-        fp = open(filename, "rb")
-        # Must overwrite CRC and sizes with correct data later
-        zinfo.CRC = CRC = 0
-        zinfo.compress_size = compress_size = 0
-        zinfo.file_size = file_size = 0
-        self.fp.write(zinfo.FileHeader())
-        if zinfo.compress_type == ZIP_DEFLATED:
-            cmpr = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
-                 zlib.DEFLATED, -15)
-        else:
-            cmpr = None
-        while 1:
-            buf = fp.read(1024 * 8)
-            if not buf:
-                break
-            file_size = file_size + len(buf)
-            CRC = crc32(buf, CRC) & 0xffffffff
-            if cmpr:
-                buf = cmpr.compress(buf)
-                compress_size = compress_size + len(buf)
-            self.fp.write(buf)
-        fp.close()
+        with open(filename, "rb") as fp:
+            # Must overwrite CRC and sizes with correct data later
+            zinfo.CRC = CRC = 0
+            zinfo.compress_size = compress_size = 0
+            zinfo.file_size = file_size = 0
+            self.fp.write(zinfo.FileHeader())
+            if zinfo.compress_type == ZIP_DEFLATED:
+                cmpr = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
+                    zlib.DEFLATED, -15)
+            else:
+                cmpr = None
+            while 1:
+                buf = fp.read(1024 * 8)
+                if not buf:
+                    break
+                file_size = file_size + len(buf)
+                CRC = crc32(buf, CRC) & 0xffffffff
+                if cmpr:
+                    buf = cmpr.compress(buf)
+                    compress_size = compress_size + len(buf)
+                self.fp.write(buf)
         if cmpr:
             buf = cmpr.flush()
             compress_size = compress_size + len(buf)