diff --git a/lldb/source/Expression/DWARFExpression.cpp b/lldb/source/Expression/DWARFExpression.cpp
index a9d365325d9e2..48022996e0e39 100644
--- a/lldb/source/Expression/DWARFExpression.cpp
+++ b/lldb/source/Expression/DWARFExpression.cpp
@@ -2331,6 +2331,10 @@ bool DWARFExpression::Evaluate(
           // not available. Fill with zeros for now by resizing the data and
           // appending it
           curr_piece.ResizeData(piece_byte_size);
+          // Note that "0" is not a correct value for the unknown bits.
+          // It would be better to also return a mask of valid bits together
+          // with the expression result, so the debugger can print missing
+          // members as "<optimized out>" or something.
           ::memset(curr_piece.GetBuffer().GetBytes(), 0, piece_byte_size);
           pieces.AppendDataToHostBuffer(curr_piece);
         } else {
@@ -2445,8 +2449,8 @@ bool DWARFExpression::Evaluate(
               return false;
             }
           }
-          op_piece_offset += piece_byte_size;
         }
+        op_piece_offset += piece_byte_size;
       }
     } break;