Machine-readable symbol reader systems including one or more shields are provided. One example machine-readable symbol reader system includes a conveyor system to convey objects bearing one or more machine-readable symbols past a first region that is transmissive to light. The system includes a machine-readable symbol reader having a housing, a window formed in the housing, and at least one optical sensor received in the housing and having a field of view that extends outward of the window, at least the window of the machine-readable symbol reader positioned relatively below the conveyor system with the field of view aligned with the first region of the conveyor system. The system can further include a shield having a frame with a plurality of apertures that are transmissive to light, the shield positioned relatively below the first region and positioned relatively above the window of the machine-readable symbol reader.