diff --git a/internal/service/neptune/cluster_instance_test.go b/internal/service/neptune/cluster_instance_test.go
index 5a8adb25965a..2a434859fd3b 100644
--- a/internal/service/neptune/cluster_instance_test.go
+++ b/internal/service/neptune/cluster_instance_test.go
@@ -350,7 +350,7 @@ data "aws_neptune_orderable_db_instance" "test" {
 
 resource "aws_neptune_parameter_group" "test" {
   name   = %[1]q
-  family = join("", ["neptune",split(".",aws_neptune_cluster.test.engine_version)[0],".",split(".",aws_neptune_cluster.test.engine_version)[1]])
+  family = join("", ["neptune", split(".", aws_neptune_cluster.test.engine_version)[0], ".", split(".", aws_neptune_cluster.test.engine_version)[1]])
 
   parameter {
     name  = "neptune_query_timeout"
diff --git a/internal/service/neptune/cluster_test.go b/internal/service/neptune/cluster_test.go
index 60bfe3ff7bcf..619ee6bf752f 100644
--- a/internal/service/neptune/cluster_test.go
+++ b/internal/service/neptune/cluster_test.go
@@ -1614,7 +1614,7 @@ resource "aws_neptune_cluster_snapshot" "test" {
 }
 
 resource "aws_neptune_cluster_parameter_group" "test" {
-  family = join("", ["neptune",split(".",aws_neptune_cluster_snapshot.test.engine_version)[0],".",split(".",aws_neptune_cluster_snapshot.test.engine_version)[1]])
+  family = join("", ["neptune", split(".", aws_neptune_cluster_snapshot.test.engine_version)[0], ".", split(".", aws_neptune_cluster_snapshot.test.engine_version)[1]])
   name   = %[1]q
 
   parameter {