diff --git a/Lib/statistics.py b/Lib/statistics.py
index a67a6d1..9359ed7 100644
--- a/Lib/statistics.py
+++ b/Lib/statistics.py
@@ -268,9 +268,7 @@
 
 def _counts(data):
     # Generate a table of sorted (value, frequency) pairs.
-    if data is None:
-        raise TypeError('None is not iterable')
-    table = collections.Counter(data).most_common()
+    table = collections.Counter(iter(data)).most_common()
     if not table:
         return table
     # Extract the values with the highest frequency.
diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py
index 3d30d88..6db821f 100644
--- a/Lib/test/test_statistics.py
+++ b/Lib/test/test_statistics.py
@@ -1355,6 +1355,14 @@
         # collections.Counter, which accepts None and returns an empty dict.
         self.assertRaises(TypeError, self.func, None)
 
+    def test_counter_data(self):
+        # Test that a Counter is treated like any other iterable.
+        data = collections.Counter([1, 1, 1, 2])
+        # Since the keys of the counter are treated as data points, not the
+        # counts, this should raise.
+        self.assertRaises(statistics.StatisticsError, self.func, data)
+
+
 
 # === Tests for variances and standard deviations ===
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 58938e0..9f8f43c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -24,6 +24,9 @@
 Library
 -------
 
+- Issue #20478: the statistics module now treats collections.Counter inputs
+  like any other iterable.
+
 - Issue #17369: get_filename was raising an exception if the filename
   parameter's RFC2231 encoding was broken in certain ways.  This was
   a regression relative to python2.