diff --git a/cmd/plan/plan.go b/cmd/plan/plan.go
index 81b74f69..b2623fdb 100644
--- a/cmd/plan/plan.go
+++ b/cmd/plan/plan.go
@@ -209,11 +209,19 @@ func CreateDesiredStateProvider(config *PlanConfig) (postgres.DesiredStateProvid
 // CreateEmbeddedPostgresForPlan creates a temporary embedded PostgreSQL instance
 // for validating the desired state schema. The instance should be stopped by the caller.
 func CreateEmbeddedPostgresForPlan(config *PlanConfig, pgVersion postgres.PostgresVersion) (*postgres.EmbeddedPostgres, error) {
-	// Start embedded PostgreSQL with matching version
+	if config.User == "" {
+		return nil, fmt.Errorf("target database user must not be empty when creating embedded postgres")
+	}
+
+	// Start embedded PostgreSQL with matching version.
+	// Use the target database username so that role references match between
+	// the desired state (embedded) and current state (target database).
+	// This ensures ALTER DEFAULT PRIVILEGES FOR ROLE <user> works correctly
+	// and that implicit owner roles match the target database. (issue #303)
 	embeddedConfig := &postgres.EmbeddedPostgresConfig{
 		Version:  pgVersion,
 		Database: "pgschema_temp",
-		Username: "pgschema",
+		Username: config.User,
 		Password: "pgschema",
 	}
 	embeddedPG, err := postgres.StartEmbeddedPostgres(embeddedConfig)
diff --git a/testdata/diff/default_privilege/issue_303_for_role/diff.sql b/testdata/diff/default_privilege/issue_303_for_role/diff.sql
new file mode 100644
index 00000000..cbdf338b
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/diff.sql
@@ -0,0 +1 @@
+ALTER DEFAULT PRIVILEGES FOR ROLE testuser IN SCHEMA public GRANT SELECT ON TABLES TO demouser;
diff --git a/testdata/diff/default_privilege/issue_303_for_role/new.sql b/testdata/diff/default_privilege/issue_303_for_role/new.sql
new file mode 100644
index 00000000..2b475a8e
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/new.sql
@@ -0,0 +1,10 @@
+-- Create roles for testing
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = 'demouser') THEN
+        CREATE ROLE demouser;
+    END IF;
+END $$;
+
+-- Grant default privileges with explicit FOR ROLE (issue #303)
+ALTER DEFAULT PRIVILEGES FOR ROLE testuser IN SCHEMA public GRANT SELECT ON TABLES TO demouser;
diff --git a/testdata/diff/default_privilege/issue_303_for_role/old.sql b/testdata/diff/default_privilege/issue_303_for_role/old.sql
new file mode 100644
index 00000000..510ca931
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/old.sql
@@ -0,0 +1,9 @@
+-- Create roles for testing
+DO $$
+BEGIN
+    IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = 'demouser') THEN
+        CREATE ROLE demouser;
+    END IF;
+END $$;
+
+-- No default privileges configured
diff --git a/testdata/diff/default_privilege/issue_303_for_role/plan.json b/testdata/diff/default_privilege/issue_303_for_role/plan.json
new file mode 100644
index 00000000..e4adfddc
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/plan.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "pgschema_version": "1.7.3",
+  "created_at": "1970-01-01T00:00:00Z",
+  "source_fingerprint": {
+    "hash": "965b1131737c955e24c7f827c55bd78e4cb49a75adfd04229e0ba297376f5085"
+  },
+  "groups": [
+    {
+      "steps": [
+        {
+          "sql": "ALTER DEFAULT PRIVILEGES FOR ROLE testuser IN SCHEMA public GRANT SELECT ON TABLES TO demouser;",
+          "type": "default_privilege",
+          "operation": "create",
+          "path": "default_privileges.testuser.TABLES.demouser"
+        }
+      ]
+    }
+  ]
+}
diff --git a/testdata/diff/default_privilege/issue_303_for_role/plan.sql b/testdata/diff/default_privilege/issue_303_for_role/plan.sql
new file mode 100644
index 00000000..cbdf338b
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/plan.sql
@@ -0,0 +1 @@
+ALTER DEFAULT PRIVILEGES FOR ROLE testuser IN SCHEMA public GRANT SELECT ON TABLES TO demouser;
diff --git a/testdata/diff/default_privilege/issue_303_for_role/plan.txt b/testdata/diff/default_privilege/issue_303_for_role/plan.txt
new file mode 100644
index 00000000..d9bf7a20
--- /dev/null
+++ b/testdata/diff/default_privilege/issue_303_for_role/plan.txt
@@ -0,0 +1,12 @@
+Plan: 1 to add.
+
+Summary by type:
+  default privileges: 1 to add
+
+Default privileges:
+  + demouser
+
+DDL to be executed:
+--------------------------------------------------
+
+ALTER DEFAULT PRIVILEGES FOR ROLE testuser IN SCHEMA public GRANT SELECT ON TABLES TO demouser;