A hanger bar assembly includes a first hanger bar member and a second hanger bar member. The first hanger bar member includes a first rail segment, a first channel segment including a first channel, and a first stoppage tab extending up above an edge of the first channel segment. The second hanger bar member includes a second rail segment positioned in the first channel of the first channel segment and a second channel segment that includes a second channel. The first rail segment is positioned in the second channel. The second hanger bar member further includes a second stoppage tab extending out in a horizontal direction. The first stoppage tab and the second stoppage tab are designed to abut against each other to prevent unintended disengagement of the first hanger bar member from the second hanger bar member.