diff --git a/Externals.cfg b/Externals.cfg
index 9ea95ff426..db33a9e67f 100644
--- a/Externals.cfg
+++ b/Externals.cfg
@@ -48,7 +48,7 @@ repo_url = https://github.com/NOAA-GSL/GSI.git
 #branch = feature/rrfs_dev
 hash = de987e08
 local_path = src/gsi
-externals = None
+externals = ../../Externals_gsi.cfg
 required = True
 
 [rrfs_utl]
diff --git a/Externals_gsi.cfg b/Externals_gsi.cfg
new file mode 100644
index 0000000000..8013635413
--- /dev/null
+++ b/Externals_gsi.cfg
@@ -0,0 +1,7 @@
+[externals_description]
+schema_version = 1.1.0
+
+[ncdiag]
+protocol = git
+required = True
+from_submodule = True