diff --git a/lib/Target/MSP430/AsmPrinter/MSP430InstPrinter.cpp b/lib/Target/MSP430/AsmPrinter/MSP430InstPrinter.cpp
index 59b448aa872..8f1ee81af04 100644
--- a/lib/Target/MSP430/AsmPrinter/MSP430InstPrinter.cpp
+++ b/lib/Target/MSP430/AsmPrinter/MSP430InstPrinter.cpp
@@ -47,6 +47,7 @@ void MSP430InstPrinter::printPCRelImmOperand(const MCInst *MI, unsigned OpNo) {
 
 void MSP430InstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
                                      const char *Modifier) {
+  assert((Modifier == 0 || Modifier[0] == 0) && "No modifiers supported");
   const MCOperand &Op = MI->getOperand(OpNo);
   if (Op.isReg()) {
     O << getRegisterName(Op.getReg());