diff --git a/builtin/providers/aws/resource_aws_config_config_rule.go b/builtin/providers/aws/resource_aws_config_config_rule.go
index e4f2e5c6b3..a5c86c334e 100644
--- a/builtin/providers/aws/resource_aws_config_config_rule.go
+++ b/builtin/providers/aws/resource_aws_config_config_rule.go
@@ -110,6 +110,7 @@ func resourceAwsConfigConfigRule() *schema.Resource {
 									"event_source": {
 										Type:     schema.TypeString,
 										Optional: true,
+										Default:  "aws.config",
 									},
 									"maximum_execution_frequency": {
 										Type:         schema.TypeString,