diff --git a/src/encounter/encounter_check.f90 b/src/encounter/encounter_check.f90
index 4fc06b559..6e5e11c88 100644
--- a/src/encounter/encounter_check.f90
+++ b/src/encounter/encounter_check.f90
@@ -1226,7 +1226,7 @@ pure subroutine sweep_sl(n, ext_ind, ibegi, iendi, ibeg, iend, lencounteri)
             ibegz(jlo:jhi) = ibeg(3,box(jlo:jhi))
             iendz(jlo:jhi) = iend(3,box(jlo:jhi))
 
-            lencounterj(jlo:jhi) =       iendy(jlo:jhi) > ibegi(2) &
+            lencounterj(jlo:jhi) =       (iendy(jlo:jhi) > ibegi(2)) &
                                    .and. (ibegy(jlo:jhi) < iendi(2)) &
                                    .and. (iendz(jlo:jhi) > ibegi(3)) &
                                    .and. (ibegz(jlo:jhi) < iendi(3))