diff --git a/gcf/custom/manifest.go b/gcf/custom/manifest.go
index cbfd58b..250500e 100644
--- a/gcf/custom/manifest.go
+++ b/gcf/custom/manifest.go
@@ -16,15 +16,46 @@ package custom
 
 import (
 	"context"
+	"fmt"
 	"path"
 	"path/filepath"
 	"sort"
+	"strings"
 
 	pb "github.com/datacommonsorg/tools/gcf/proto"
 	"google.golang.org/protobuf/encoding/protojson"
 	"google.golang.org/protobuf/proto"
 )
 
+func isAlphaNumeric(c byte) bool {
+	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9')
+}
+
+func getImportGroupName(root string) (string, error) {
+	importGroup := path.Base(root)
+
+	// Remove alphanumeric characters since they aren't handled well by GCS.
+	var builder strings.Builder
+	for i := 0; i < len(importGroup); i++ {
+		if isAlphaNumeric(importGroup[i]) {
+			builder.WriteByte(importGroup[i])
+		}
+	}
+	result := builder.String()
+	if len(result) == 0 {
+		return "", fmt.Errorf("importGroup contains no alphanumeric characters: %s", root)
+	}
+
+	// IMPORTANT NOTE:
+	// importGroup has a character constraint of 20 due to internal limitations.
+	// https://cloud.google.com/storage-transfer/docs/known-limitations-transfer#tsop-max-path
+	if len(result) > 20 {
+		result = result[:20]
+	}
+
+	return result, nil
+}
+
 func computeTable(bucket, root, im, tab string, table *Table) *pb.ExternalTable {
 	bigstoreTmcf := filepath.Join("/bigstore", bucket, root, "data", im, tab, table.tmcf)
 	bigstoreCsv := []string{}
@@ -107,11 +138,9 @@ func ComputeManifest(
 	layout *Layout,
 ) (*pb.DataCommonsManifest, error) {
 	root := layout.root
-	importGroup := path.Base(root)
-	// IMPORTANT NOTE:
-	// importGroup has a character constraint of 20 due to internal limitations.
-	if len(importGroup) > 20 {
-		importGroup = importGroup[:20]
+	importGroup, err := getImportGroupName(root)
+	if err != nil {
+		return nil, err
 	}
 
 	// Init manifest
diff --git a/gcf/custom/manifest_test.go b/gcf/custom/manifest_test.go
index 6da50dc..d7887e3 100644
--- a/gcf/custom/manifest_test.go
+++ b/gcf/custom/manifest_test.go
@@ -36,10 +36,10 @@ func (g *TestReader) ListObjects(
 
 func (g *TestReader) ReadObject(
 	ctx context.Context, bucket, object string) ([]byte, error) {
-	if bucket == "test-bucket" && object == "parent/demo/data/provenance.json" {
+	if bucket == "test-bucket" && object == "parent/sustainable_systems_lab/data/provenance.json" {
 		return []byte(`{"name":"data source", "url": "test.com"}`), nil
 	}
-	if bucket == "test-bucket" && object == "parent/demo/data/import1/provenance.json" {
+	if bucket == "test-bucket" && object == "parent/sustainable_systems_lab/data/import1/provenance.json" {
 		return []byte(`{"name":"foo_dataset", "url": "test.com/bar"}`), nil
 	}
 	return []byte{}, nil
@@ -55,7 +55,7 @@ func TestComputeManifest(t *testing.T) {
 		{
 			"test-bucket",
 			&Layout{
-				root: "parent/demo",
+				root: "parent/sustainable_systems_lab",
 				prov: "provenance.json",
 				imports: map[string]*Import{
 					"import1": {
diff --git a/gcf/custom/test_data/golden.textproto b/gcf/custom/test_data/golden.textproto
index 3a37ac3..725baab 100644
--- a/gcf/custom/test_data/golden.textproto
+++ b/gcf/custom/test_data/golden.textproto
@@ -2,52 +2,52 @@ import: {
   import_name: "foo_dataset"
   provenance_url: "test.com/bar"
   category: STATS
-  import_groups: "demo"
-  mcf_proto_url: "/bigstore/test-bucket/parent/demo/data/import1/ocean/graph.tfrecord@*.gz"
-  mcf_proto_url: "/bigstore/test-bucket/parent/demo/data/import1/smokepm/graph.tfrecord@*.gz"
+  import_groups: "sustainablesystemsla"
+  mcf_proto_url: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/ocean/graph.tfrecord@*.gz"
+  mcf_proto_url: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/smokepm/graph.tfrecord@*.gz"
   table: {
-    mapping_path: "/bigstore/test-bucket/parent/demo/data/import1/ocean/sea.tmcf"
-    csv_path: "/bigstore/test-bucket/parent/demo/data/import1/ocean/river.csv"
-    csv_path: "/bigstore/test-bucket/parent/demo/data/import1/ocean/lake.csv"
+    mapping_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/ocean/sea.tmcf"
+    csv_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/ocean/river.csv"
+    csv_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/ocean/lake.csv"
   }
   table: {
-    mapping_path: "/bigstore/test-bucket/parent/demo/data/import1/smokepm/data.tmcf"
-    csv_path: "/bigstore/test-bucket/parent/demo/data/import1/smokepm/1.csv"
-    csv_path: "/bigstore/test-bucket/parent/demo/data/import1/smokepm/2.csv"
+    mapping_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/smokepm/data.tmcf"
+    csv_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/smokepm/1.csv"
+    csv_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/smokepm/2.csv"
   }
   resolution_info: {
     uses_id_resolver: true
   }
-  automated_mcf_generation_by: "demo"
+  automated_mcf_generation_by: "sustainablesystemsla"
   dataset_name: "foo_dataset"
 }
 import: {
   import_name: "import2"
   provenance_url: "test.com"
   category: STATS
-  import_groups: "demo"
-  mcf_proto_url: "/bigstore/test-bucket/parent/demo/data/import2/solar/graph.tfrecord@*.gz"
+  import_groups: "sustainablesystemsla"
+  mcf_proto_url: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import2/solar/graph.tfrecord@*.gz"
   table: {
-    mapping_path: "/bigstore/test-bucket/parent/demo/data/import2/solar/data.tmcf"
-    csv_path: "/bigstore/test-bucket/parent/demo/data/import2/solar/output.csv"
+    mapping_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import2/solar/data.tmcf"
+    csv_path: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import2/solar/output.csv"
   }
   resolution_info: {
     uses_id_resolver: true
   }
-  automated_mcf_generation_by: "demo"
+  automated_mcf_generation_by: "sustainablesystemsla"
   dataset_name: "import2"
 }
 import: {
   import_name: "schema"
   provenance_url: "test.com"
   category: SCHEMA
-  mcf_url: "/bigstore/test-bucket/parent/demo/data/import1/*.mcf*"
-  mcf_url: "/bigstore/test-bucket/parent/demo/data/import2/*.mcf*"
-  import_groups: "demo"
-  dataset_name: "demo"
+  mcf_url: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import1/*.mcf*"
+  mcf_url: "/bigstore/test-bucket/parent/sustainable_systems_lab/data/import2/*.mcf*"
+  import_groups: "sustainablesystemsla"
+  dataset_name: "sustainablesystemsla"
 }
 import_groups: {
-  name: "demo"
+  name: "sustainablesystemsla"
   description: "Custom DC import group"
   is_custom_dc: true
 }