diff --git a/src/PIL/PcdImagePlugin.py b/src/PIL/PcdImagePlugin.py
index ac53f616e..7f9ab525c 100644
--- a/src/PIL/PcdImagePlugin.py
+++ b/src/PIL/PcdImagePlugin.py
@@ -32,7 +32,7 @@ class PcdImageFile(ImageFile.ImageFile):
         assert self.fp is not None
 
         self.fp.seek(2048)
-        s = self.fp.read(2048)
+        s = self.fp.read(1539)
 
         if not s.startswith(b"PCD_"):
             msg = "not a PCD file"