diff --git a/test/Scripts/coff-dump.py.bat b/test/Scripts/coff-dump.py.bat
index cc83eba..56428e1 100644
--- a/test/Scripts/coff-dump.py.bat
+++ b/test/Scripts/coff-dump.py.bat
@@ -1,4 +1,7 @@
 @echo off
 
-%PYTHON_EXECUTABLE% %LLVM_SRC_ROOT%\test\Scripts\coff-dump.py %1 %2 %3 %4 %5 %6 %7 %8 %9
+@rem We need to set -u to treat stdin as binary. Python 3 has support for doing
+@rem this in code, but I haven't found a way to do this in 2.6 yet.
+
+%PYTHON_EXECUTABLE% -u %LLVM_SRC_ROOT%\test\Scripts\coff-dump.py %1 %2 %3 %4 %5 %6 %7 %8 %9