diff --git a/src/PIL/IcnsImagePlugin.py b/src/PIL/IcnsImagePlugin.py
index 0e1b20596..6f26b90fa 100644
--- a/src/PIL/IcnsImagePlugin.py
+++ b/src/PIL/IcnsImagePlugin.py
@@ -365,11 +365,12 @@ if __name__ == "__main__":
         print("Syntax: python IcnsImagePlugin.py [file]")
         sys.exit()
 
-    imf = IcnsImageFile(open(sys.argv[1], "rb"))
-    for size in imf.info["sizes"]:
-        imf.size = size
-        imf.save("out-%s-%s-%s.png" % size)
-    im = Image.open(sys.argv[1])
-    im.save("out.png")
-    if sys.platform == "windows":
-        os.startfile("out.png")
+    with open(sys.argv[1], "rb") as fp:
+        imf = IcnsImageFile(fp)
+        for size in imf.info["sizes"]:
+            imf.size = size
+            imf.save("out-%s-%s-%s.png" % size)
+        im = Image.open(sys.argv[1])
+        im.save("out.png")
+        if sys.platform == "windows":
+            os.startfile("out.png")