diff --git a/.gitmodules b/.gitmodules
index 0c3b70cc3f..c03280d702 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -28,8 +28,10 @@
   branch = emc/develop
 [submodule "MOM6"]
   path = MOM6-interface/MOM6
-  url = https://github.com/NOAA-EMC/MOM6
-  branch = dev/emc
+  #url = https://github.com/NOAA-EMC/MOM6
+  #branch = dev/emc
+  url = https://github.com/jiandewang/MOM6
+  branch = feature/update-to-GFDL-20210402
 [submodule "CICE"]
   path = CICE-interface/CICE
   url = https://github.com/NOAA-EMC/CICE
diff --git a/MOM6-interface/MOM6 b/MOM6-interface/MOM6
index 3703ca7ddc..c549ae9d93 160000
--- a/MOM6-interface/MOM6
+++ b/MOM6-interface/MOM6
@@ -1 +1 @@
-Subproject commit 3703ca7ddc3dbd18d205581d32e47aa828fed976
+Subproject commit c549ae9d93531b104492654d257e4949293d3c3a
diff --git a/tests/default_vars.sh b/tests/default_vars.sh
index d2b38e16d9..4e6462191d 100755
--- a/tests/default_vars.sh
+++ b/tests/default_vars.sh
@@ -585,6 +585,7 @@ export MOM6_REPRO_LA='False'
 export MOM6_THERMO_SPAN='False'
 # no WW3
 export MOM6_USE_WAVES='False'
+export MOM6_ALLOW_LANDMASK_CHANGES='False'
 
 # CICE6 defaults; 1 degree
 export NPROC_ICE='12'
@@ -674,8 +675,8 @@ export coupling_interval_fast_sec=${CPL_FAST}
 export RESTART_N=${FHMAX}
 export CPLMODE='nems_orig_data'
 export cap_dbug_flag="0"
-export use_coldstart=".false."
-export use_mommesh=".false."
+export use_coldstart="false"
+export use_mommesh="false"
 export RUNTYPE='startup'
 export flux_convergence='0.0'
 export flux_iteration='2'
@@ -698,6 +699,7 @@ export MOM6_REPRO_LA='False'
 export MOM6_THERMO_SPAN='False'
 # no WW3
 export MOM6_USE_WAVES='False'
+export MOM6_ALLOW_LANDMASK_CHANGES='False'
 
 # CICE6 defaults; 1 degree
 export MESHOCN_ICE="mesh.mx${OCNRES}.nc"
diff --git a/tests/edit_inputs.sh b/tests/edit_inputs.sh
index 0b0a9527fc..e7ecb60649 100755
--- a/tests/edit_inputs.sh
+++ b/tests/edit_inputs.sh
@@ -39,6 +39,7 @@ function edit_mom_input {
       -e "s/MOM6_THERMO_SPAN/$MOM6_THERMO_SPAN/g" \
       -e "s/MOM6_REPRO_LA/$MOM6_REPRO_LA/g" \
       -e "s/MOM6_USE_WAVES/$MOM6_USE_WAVES/g" \
+      -e "s/MOM6_ALLOW_LANDMASK_CHANGES/$MOM6_ALLOW_LANDMASK_CHANGES/g" \
       -e "s/NX_GLB/$NX_GLB/g" \
       -e "s/NY_GLB/$NY_GLB/g" \
       -e "s/CHLCLIM/$CHLCLIM/g"
diff --git a/tests/parm/MOM_input_template_025 b/tests/parm/MOM_input_template_025
index aa1da78029..1340db5b66 100644
--- a/tests/parm/MOM_input_template_025
+++ b/tests/parm/MOM_input_template_025
@@ -148,6 +148,8 @@ TOPO_FILE = "ocean_topog.nc"    ! default = "topog.nc"
                                 ! The file from which the bathymetry is read.
 TOPO_EDITS_FILE = "All_edits.nc" ! default = ""
                                 ! The file from which to read a list of i,j,z topography overrides.
+ALLOW_LANDMASK_CHANGES = MOM6_ALLOW_LANDMASK_CHANGES   ! default = "False"
+                                ! If true, allow topography overrides to change ocean points to land
 MAXIMUM_DEPTH = 6500.0          !   [m]
                                 ! The maximum depth of the ocean.
 MINIMUM_DEPTH = 9.5             !   [m] default = 0.0
diff --git a/tests/parm/MOM_input_template_050 b/tests/parm/MOM_input_template_050
index 46780dfc82..ceff6e98d4 100644
--- a/tests/parm/MOM_input_template_050
+++ b/tests/parm/MOM_input_template_050
@@ -147,6 +147,8 @@ TOPO_CONFIG = "file"            !
                                 !     USER - call a user modified routine.
 TOPO_FILE = "ocean_topog.nc"    ! default = "topog.nc"
                                 ! The file from which the bathymetry is read.
+ALLOW_LANDMASK_CHANGES = MOM6_ALLOW_LANDMASK_CHANGES   ! default = "False"
+                                ! If true, allow topography overrides to change ocean points to land
 MAXIMUM_DEPTH = 6500.0          !   [m]
                                 ! The maximum depth of the ocean.
 MINIMUM_DEPTH = 9.5             !   [m] default = 0.0
diff --git a/tests/parm/MOM_input_template_100 b/tests/parm/MOM_input_template_100
index ffb4c7de5e..f93bf693a0 100644
--- a/tests/parm/MOM_input_template_100
+++ b/tests/parm/MOM_input_template_100
@@ -140,6 +140,8 @@ TOPO_CONFIG = "file"            !
                                 !     USER - call a user modified routine.
 TOPO_EDITS_FILE = "topo_edits_011818.nc" ! default = ""
                                 ! The file from which to read a list of i,j,z topography overrides.
+ALLOW_LANDMASK_CHANGES = MOM6_ALLOW_LANDMASK_CHANGES   ! default = "False"
+                                ! If true, allow topography overrides to change ocean points to land
 MAXIMUM_DEPTH = 6500.0          !   [m]
                                 ! The maximum depth of the ocean.
 MINIMUM_DEPTH = 9.5             !   [m] default = 0.0