diff --git a/src/PIL/BmpImagePlugin.py b/src/PIL/BmpImagePlugin.py
index a1ed80aee..7bd5a0308 100644
--- a/src/PIL/BmpImagePlugin.py
+++ b/src/PIL/BmpImagePlugin.py
@@ -263,7 +263,7 @@ class BmpImageFile(ImageFile.ImageFile):
         # read 14 bytes: magic number, filesize, reserved, header final offset
         head_data = self.fp.read(14)
         # choke if the file does not have the required magic bytes
-        if not _accept(head_data[0:2]):
+        if not _accept(head_data):
             raise SyntaxError("Not a BMP file")
         # read the start position of the BMP image data (u32)
         offset = i32(head_data[10:14])