diff --git a/PIL/Image.py b/PIL/Image.py
index caa66ea0d..af6dac1c4 100644
--- a/PIL/Image.py
+++ b/PIL/Image.py
@@ -550,7 +550,7 @@ class Image(object):
         try:
             self.fp.close()
         except Exception as msg:
-            logger.debug("Error closing: %s" % msg)
+            logger.debug("Error closing: %s", msg)
 
         # Instead of simply setting to None, we're setting up a
         # deferred error that will better explain that the core image