diff --git a/Library/Homebrew/mach.rb b/Library/Homebrew/mach.rb
index ff3b76d2d9239d0be7206e1fe20132cea15c7796..de38d296bf2b731774d5fa84406e30ff7e643013 100644
--- a/Library/Homebrew/mach.rb
+++ b/Library/Homebrew/mach.rb
@@ -60,7 +60,7 @@ module MachO
     offsets = []
     mach_data = []
 
-    header = (read(8) || "").unpack("N2")
+    header = read(8).unpack("N2")
     case header[0]
     when 0xcafebabe # universal
       header[1].times do |i|