diff --git a/lib/Target/ARM/ARMTargetMachine.cpp b/lib/Target/ARM/ARMTargetMachine.cpp
index 1cef366..d8dfb71 100644
--- a/lib/Target/ARM/ARMTargetMachine.cpp
+++ b/lib/Target/ARM/ARMTargetMachine.cpp
@@ -45,7 +45,8 @@
   case Triple::MinGW64:
   case Triple::Cygwin:
   case Triple::Win32:
-    assert(0 && "ARM does not support Windows COFF format"); break;
+    llvm_unreachable("ARM does not support Windows COFF format");
+    return NULL;
   default:
     return createELFStreamer(Ctx, TAB, _OS, _Emitter, RelaxAll);
   }