diff --git a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
index e2df2ab16c0..1d300a66c5d 100644
--- a/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ b/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -2778,7 +2778,8 @@ int ARMAsmParser::tryParseShiftRegister(
                                SmallVectorImpl<MCParsedAsmOperand*> &Operands) {
   SMLoc S = Parser.getTok().getLoc();
   const AsmToken &Tok = Parser.getTok();
-  assert(Tok.is(AsmToken::Identifier) && "Token is not an Identifier");
+  if (Tok.isNot(AsmToken::Identifier))
+    return -1; 
 
   std::string lowerCase = Tok.getString().lower();
   ARM_AM::ShiftOpc ShiftTy = StringSwitch<ARM_AM::ShiftOpc>(lowerCase)
diff --git a/test/MC/ARM/invalid-vector-index.s b/test/MC/ARM/invalid-vector-index.s
new file mode 100644
index 00000000000..b58e1bdcc30
--- /dev/null
+++ b/test/MC/ARM/invalid-vector-index.s
@@ -0,0 +1,5 @@
+@ RUN: not llvm-mc -triple=armv7-apple-darwin < %s 2>&1 | FileCheck %s
+
+ldrd r6, r7 [r2, #15]
+
+@ CHECK: error: immediate value expected for vector index