diff --git a/morituri/rip/cd.py b/morituri/rip/cd.py
index 09b5803..02c14b2 100644
--- a/morituri/rip/cd.py
+++ b/morituri/rip/cd.py
@@ -431,7 +431,7 @@ Install pycdio and run 'rip offset find' to detect your drive's offset.
                     raise
 
                 self.stdout.write('Peak level: %.2f %%\n' % (
-                    math.sqrt(trackResult.peak) * 100.0, ))
+                    float(math.sqrt(trackResult.peak) * 100.0, )))
                 self.stdout.write('Rip quality: %.2f %%\n' % (
                     trackResult.quality * 100.0, ))