diff --git a/test/Scripts/macho-dump.bat b/test/Scripts/macho-dump.bat
index 94859f9115b..81484f67d70 100644
--- a/test/Scripts/macho-dump.bat
+++ b/test/Scripts/macho-dump.bat
@@ -1,7 +1,7 @@
 @echo off
 
-@rem The -t here is just to avoid infinite looping if %PYTHON_EXECUTABLE% isn't set
-@rem for some reason.
+@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% -t %LLVM_SRC_ROOT%\test\Scripts\macho-dump %1 %2 %3 %4 %5 %6 %7 %8 %9
+%PYTHON_EXECUTABLE% -u %LLVM_SRC_ROOT%\test\Scripts\macho-dump %1 %2 %3 %4 %5 %6 %7 %8 %9