diff --git a/lib/Target/TargetData.cpp b/lib/Target/TargetData.cpp
index 48fca1e..6786af3 100644
--- a/lib/Target/TargetData.cpp
+++ b/lib/Target/TargetData.cpp
@@ -164,13 +164,11 @@
 
       // Get the array index and the size of each array element.
       // Both must be known constants, or this will fail.
-      // Also, the arrayIdx needs to be sign-extended from uint
-      // to the machine register size if the reg. size > sizeof(uint).
+      // Also, the arrayIdx needs to be sign-extended from 32 bits to uint64_t
+      // since uint is not normally sign-extended when cast to uint64_t.
       uint64_t elementSize = this->getTypeSize(Ty);
       uint64_t arrayIdx = cast<ConstantUInt>(Idx[CurIDX])->getValue();
-      if (getIntegerRegize() > sizeof(uint)) {
-        arrayIdx = (uint64_t) (int) arrayIdx; // sign-extend from 32 to 64 bits
-      }
+      arrayIdx = (uint64_t) (int) arrayIdx; // sign-extend from 32 to 64 bits
       Result += arrayIdx * elementSize;
 
     } else if (const StructType *STy = dyn_cast<const StructType>(Ty)) {