An exhaust gas recirculation cooler that includes an inlet tank, an outlet tank, and an exhaust gas flow conduit in fluid communication with the inlet tank and the outlet tank. The exhaust gas flow conduit includes a first end, a second end, a first narrow side, a second narrow side, a first channel adjacent the first narrow side and extending between the first end and the second end, a second channel adjacent the second narrow side and extending between the first end and the second end, and a plurality of third channels located between the first channel and the second channel and extending between the first end and the second end. At least one of the inlet tank and the outlet tank includes a wall that inhibits exhaust gas from flowing through the first channel while allowing exhaust gas flow through the plurality of third channels.