diff --git a/ccpp/physics b/ccpp/physics
index 5c9c75436..0db75636f 160000
--- a/ccpp/physics
+++ b/ccpp/physics
@@ -1 +1 @@
-Subproject commit 5c9c75436df4796ace8d951d72f0846859bdc148
+Subproject commit 0db75636f26c51b23b97c75c0a515885219bd24d
diff --git a/gfsphysics/GFS_layer/GFS_typedefs.F90 b/gfsphysics/GFS_layer/GFS_typedefs.F90
index 3c1252b1e..6e2fa4945 100644
--- a/gfsphysics/GFS_layer/GFS_typedefs.F90
+++ b/gfsphysics/GFS_layer/GFS_typedefs.F90
@@ -7110,6 +7110,9 @@ subroutine interstitial_phys_reset (Interstitial, Model)
     !
   end subroutine interstitial_phys_reset
 
+  ! DH* 20200901: this routine is no longer used by CCPP's GFS_debug.F90. When new variables are
+  ! added to the GFS_interstitial_type, it is best to add the variable to both interstitial_print
+  ! below and to GFS_interstitialtoscreen in ccpp/physics/physics/GFS_debug.F90
   subroutine interstitial_print(Interstitial, Model, mpirank, omprank, blkno)
     !
     implicit none