diff --git a/optimize_images/optimize_images.py b/optimize_images/optimize_images.py
index 7a750d2..87fea71 100644
--- a/optimize_images/optimize_images.py
+++ b/optimize_images/optimize_images.py
@@ -19,7 +19,7 @@ logger = logging.getLogger(__name__)
 # A list of file types with their respective commands
 COMMANDS = [
     ('.jpg', 'jpegtran -copy none -optimize -outfile "{filename}" "{filename}"'),
-    ('.png', 'optipng "{filename}"'),
+    ('.png', 'optipng --quiet "{filename}"'),
 ]
 
 def optimize_images(pelican):