diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index b2d9ab250d5..a440667e00f 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -841,8 +841,11 @@ void PPCDarwinAsmPrinter::EmitStartOfAsmFile(Module &M) {
   assert(Directive <= PPC::DIR_64 && "Directive out of range.");
   
   // FIXME: This is a total hack, finish mc'izing the PPC backend.
-  if (OutStreamer.hasRawTextSupport())
+  if (OutStreamer.hasRawTextSupport()) {
+    assert(Directive < sizeof(CPUDirectives) / sizeof(*CPUDirectives) &&
+           "CPUDirectives[] might not be up-to-date!");
     OutStreamer.EmitRawText("\t.machine " + Twine(CPUDirectives[Directive]));
+  }
 
   // Prime text sections so they are adjacent.  This reduces the likelihood a
   // large data or debug section causes a branch to exceed 16M limit.