diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index 3e19ecff090..0e0572383d3 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -1488,11 +1488,20 @@ def test_data(self):
     # if we change data we need to remove content-length header
     # (cause it's most probably calculated for previous value)
     def test_setting_data_should_remove_content_length(self):
-        self.assertFalse("Content-length" in self.get.unredirected_hdrs)
+        self.assertNotIn("Content-length", self.get.unredirected_hdrs)
         self.get.add_unredirected_header("Content-length", 42)
         self.assertEqual(42, self.get.unredirected_hdrs["Content-length"])
         self.get.data = "spam"
-        self.assertFalse("Content-length" in self.get.unredirected_hdrs)
+        self.assertNotIn("Content-length", self.get.unredirected_hdrs)
+
+    # issue 17485 same for deleting data.
+    def test_deleting_data_should_remove_content_length(self):
+        self.assertNotIn("Content-length", self.get.unredirected_hdrs)
+        self.get.data = 'foo'
+        self.get.add_unredirected_header("Content-length", 3)
+        self.assertEqual(3, self.get.unredirected_hdrs["Content-length"])
+        del self.get.data
+        self.assertNotIn("Content-length", self.get.unredirected_hdrs)
 
     def test_get_full_url(self):
         self.assertEqual("http://www.python.org/~jeremy/",
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index 90731cb0593..8b3cdf9d2cc 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -296,7 +296,7 @@ def data(self, data):
 
     @data.deleter
     def data(self):
-        self._data = None
+        self.data = None
 
     def _parse(self):
         self.type, rest = splittype(self.full_url)
diff --git a/Misc/ACKS b/Misc/ACKS
index 600e0bf03c5..21f2cd57f25 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1341,6 +1341,7 @@ Steven Work
 Gordon Worley
 Darren Worrall
 Thomas Wouters
+Daniel Wozniak
 Heiko Wundram
 Doug Wyatt
 Robert Xiao
diff --git a/Misc/NEWS b/Misc/NEWS
index e7c59b18b5e..8e46c60e9ee 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -292,6 +292,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #17485: Also delete the Request Content-Length header if the data
+  attribute is deleted.  (Follow on to issue 16464).
+
 - Issue #15927: CVS now correctly parses escaped newlines and carriage
   when parsing with quoting turned off.