diff --git a/.changelog/4184.txt b/.changelog/4184.txt
new file mode 100644
index 0000000000..47364a2b8d
--- /dev/null
+++ b/.changelog/4184.txt
@@ -0,0 +1,4 @@
+```release-note:bug
+storage - added length check for `cors` for the resource `resource_storage_bucket`
+
+```
diff --git a/google-beta/resource_storage_bucket.go b/google-beta/resource_storage_bucket.go
index 656cbb9ad2..18411c22b3 100644
--- a/google-beta/resource_storage_bucket.go
+++ b/google-beta/resource_storage_bucket.go
@@ -844,6 +844,9 @@ func resourceStorageBucketStateImporter(d *schema.ResourceData, meta interface{}
 
 func expandCors(configured []interface{}) []*storage.BucketCors {
 	corsRules := make([]*storage.BucketCors, 0, len(configured))
+	if len(corsRules) == 0 {
+		return nil
+	}
 	for _, raw := range configured {
 		data := raw.(map[string]interface{})
 		corsRule := storage.BucketCors{