diff --git a/src/p_slopes.c b/src/p_slopes.c
index 6aca116a58f295eec7c69d3a9fcc9611914f461a..1c0ee81a7e9453d204049d2f0ab5986a07849edb 100644
--- a/src/p_slopes.c
+++ b/src/p_slopes.c
@@ -566,6 +566,7 @@ static void line_SpawnViaMapthingVertexes(const int linenum, const boolean spawn
 	case TMSP_BACKCEILING:
 		slopetoset = &line->backsector->c_slope;
 		side = &sides[line->sidenum[1]];
+		break;
 	default:
 		return;
 	}