diff --git a/src/grid_mod.F90 b/src/grid_mod.F90
index dc58b2aba8e8ed622a8b74a615742a7086d5089d..b85b9b9b4b6af46c34d8af27d449b4c2eef2cab9 100644
--- a/src/grid_mod.F90
+++ b/src/grid_mod.F90
@@ -543,9 +543,9 @@ CONTAINS
     ! We remove one point more if ExB is on since the moving grid
     ! can go up to kx=+-(kx_max+deltakx/2)
     IF (ABS(ExBrate) .GT. 0) THEN
-      two_third_kxmax = 2._xp/3._xp*(kx_max)
+      two_third_kxmax = 2._xp/3._xp*abs(kx_min)
     ELSE
-      two_third_kxmax = 2._xp/3._xp*kx_max
+      two_third_kxmax = 2._xp/3._xp*abs(kx_min)
     ENDIF
     ! Antialiasing filter
     DO iky = 1,local_nky