diff --git a/Externals_CAM.cfg b/Externals_CAM.cfg
index 5be47f26cb..4992ed9946 100644
--- a/Externals_CAM.cfg
+++ b/Externals_CAM.cfg
@@ -91,5 +91,12 @@ repo_url = https://github.com/ESCOMP/HEMCO_CESM.git
 required = True
 externals = Externals_HCO.cfg
 
+[cloud_j]
+local_path = src/chemistry/cloud_j
+branch = cesm
+protocol = git
+repo_url = https://github.com/geoschem/CLOUD-J.git
+required = True
+
 [externals_description]
 schema_version = 1.0.0
diff --git a/bld/configure b/bld/configure
index da7330152a..8d4e967470 100755
--- a/bld/configure
+++ b/bld/configure
@@ -1406,7 +1406,7 @@ if ($chem_pkg =~ '_mam3') {
 
 # Set GEOS-Chem CPP definitions here
 if ($chem_pkg =~ 'geoschem') {
-    $chem_cppdefs .= ' -DEXTERNAL_GRID -DEXTERNAL_FORCING -DLINUX_IFORT -DUSE_REAL8 -DMODEL_ -DMODEL_CESM';
+    $chem_cppdefs .= ' -DEXTERNAL_GRID -DEXTERNAL_FORCING -DLINUX_IFORT -DUSE_REAL8 -DMODEL_ -DMODEL_CESM -DMODEL_GEOSCHEM';
     $chem_nadv = 267; # includes GC advected species (233), CO2 (1), and MAM aerosols (33)
 }
 
@@ -2167,6 +2167,11 @@ sub write_filepath
         print $fh "$chem_src_dir\n";
     }
  
+    # Cloud-J for computing J-values in chemistry; currently only built for GEOS-Chem
+    if ($chem_pkg =~ 'geoschem') {
+	print $fh "$camsrcdir/src/chemistry/cloud_j/src/Core\n";
+    }
+
     # GEOS-Chem must be prior to Mozart
     if ($chem_pkg =~ 'geoschem') {	
 	print $fh "$chem_src_dir/geoschem_src/GeosCore\n";