diff --git a/biogeophys/FatesPlantRespPhotosynthMod.F90 b/biogeophys/FatesPlantRespPhotosynthMod.F90
index 2fae4eceb2..4b181ed7b3 100644
--- a/biogeophys/FatesPlantRespPhotosynthMod.F90
+++ b/biogeophys/FatesPlantRespPhotosynthMod.F90
@@ -938,7 +938,7 @@ subroutine LeafLayerPhotosynthesis(f_sun_lsl,         &  ! in
      
      if ( parsun_lsl <= 0._r8 ) then  ! night time
 
-        anet_av_out = 0._r8
+        anet_av_out = -lmr
         psn_out     = 0._r8
         rstoma_out  = min(rsmax0, 1._r8/bbb * cf)