diff --git a/hgext/churn.py b/hgext/churn.py
--- a/hgext/churn.py
+++ b/hgext/churn.py
@@ -148,7 +148,8 @@ def churn(ui, repo, *pats, **opts):
     sortkey = ((not opts.get('sort')) and (lambda x: -x[1]) or None)
     rate.sort(key=sortkey)
 
-    maxcount = float(max([v for k, v in rate]))
+    # Be careful not to have a zero maxcount (issue833)
+    maxcount = float(max([v for k, v in rate])) or 1.0
     maxname = max([len(k) for k, v in rate])
 
     ttywidth = util.termwidth()
diff --git a/tests/test-churn b/tests/test-churn
--- a/tests/test-churn
+++ b/tests/test-churn
@@ -50,3 +50,13 @@ COLUMNS=40 hg churn
 echo % churn by hour
 hg churn -f '%H' -s
 
+cd ..
+
+# issue 833: ZeroDivisionError
+hg init issue-833
+cd issue-833
+touch foo
+hg ci -Am foo
+# this was failing with a ZeroDivisionError
+hg churn
+cd ..
diff --git a/tests/test-churn.out b/tests/test-churn.out
--- a/tests/test-churn.out
+++ b/tests/test-churn.out
@@ -28,3 +28,5 @@ 06      1 ****************
 09      2 *********************************
 12      4 ******************************************************************
 13      1 ****************
+adding foo
+test      0