diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index 8712fc9..08a6536 100644
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -153,12 +153,10 @@
 
 uint64_t TargetData::getIndexedOffset(const Type *ptrTy,
 				      const std::vector<Value*> &Idx) const {
-  const PointerType *PtrTy = cast<const PointerType>(ptrTy);
+  const Type *Ty = ptrTy;
+  assert(isa<PointerType>(Ty) && "Illegal argument for getIndexedOffset()");
   uint64_t Result = 0;
 
-  // Get the type pointed to...
-  const Type *Ty = PtrTy->getElementType();
-
   for (unsigned CurIDX = 0; CurIDX < Idx.size(); ++CurIDX) {
     if (Idx[CurIDX]->getType() == Type::UIntTy) {
       // Get the array index and the size of each array element.
@@ -166,7 +164,10 @@
       unsigned arrayIdx = cast<ConstantUInt>(Idx[CurIDX])->getValue();
       uint64_t elementSize = this->getTypeSize(Ty);
       Result += arrayIdx * elementSize;
-      
+
+      // Update Ty to refer to current element
+      Ty = cast<SequentialType>(Ty)->getElementType();
+
     } else if (const StructType *STy = dyn_cast<const StructType>(Ty)) {
       assert(Idx[CurIDX]->getType() == Type::UByteTy && "Illegal struct idx");
       unsigned FieldNo = cast<ConstantUInt>(Idx[CurIDX])->getValue();
@@ -177,7 +178,7 @@
       // Add in the offset, as calculated by the structure layout info...
       assert(FieldNo < Layout->MemberOffsets.size() &&"FieldNo out of range!");
       Result += Layout->MemberOffsets[FieldNo];
-      
+
       // Update Ty to refer to current element
       Ty = STy->getElementTypes()[FieldNo];