diff --git a/thinkplot/__init__.py b/thinkplot/__init__.py
old mode 100755
new mode 100644
diff --git a/thinkplot/thinkplot.py b/thinkplot/thinkplot.py
old mode 100755
new mode 100644
diff --git a/thinkstats2/__init__.py b/thinkstats2/__init__.py
old mode 100755
new mode 100644
diff --git a/thinkstats2/thinkstats2.py b/thinkstats2/thinkstats2.py
index b1b54d1bb..cea3d532b 100644
--- a/thinkstats2/thinkstats2.py
+++ b/thinkstats2/thinkstats2.py
@@ -1225,7 +1225,7 @@ def PercentileRanks(self, xs):
 
         returns: array of percentile ranks in the range 0 to 100
         """
-        return self.Probs(x) * 100
+        return self.Probs(xs) * 100
 
     def Random(self):
         """Chooses a random value from this distribution."""