diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index 22ee46bfc..9057c5f8d 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -358,7 +358,7 @@ _initialized = 0
 
 
 def preinit():
-    "Explicitly load standard file format drivers."
+    """Explicitly load standard file format drivers."""
 
     global _initialized
     if _initialized >= 1:
@@ -2246,7 +2246,7 @@ class ImageTransformHandler(object):
 # Debugging
 
 def _wedge():
-    "Create greyscale wedge (for debugging only)"
+    """Create greyscale wedge (for debugging only)"""
 
     return Image()._new(core.wedge("L"))
 
diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index 621e19b9a..9eb364206 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -663,7 +663,7 @@ _OUTMODES = {
 
 
 def putchunk(fp, cid, *data):
-    "Write a PNG chunk (including CRC field)"
+    """Write a PNG chunk (including CRC field)"""
 
     data = b"".join(data)
 
diff --git a/src/PIL/SpiderImagePlugin.py b/src/PIL/SpiderImagePlugin.py
index d89a3e1b3..d502779e2 100644
--- a/src/PIL/SpiderImagePlugin.py
+++ b/src/PIL/SpiderImagePlugin.py
@@ -200,7 +200,7 @@ class SpiderImageFile(ImageFile.ImageFile):
 
 # given a list of filenames, return a list of images
 def loadImageSeries(filelist=None):
-    " create a list of Image.images for use in montage "
+    """create a list of Image.images for use in montage"""
     if filelist is None or len(filelist) < 1:
         return