diff --git a/api/v1alpha1/tenantcontrolplane_funcs.go b/api/v1alpha1/tenantcontrolplane_funcs.go
index bd30a96..d2a4152 100644
--- a/api/v1alpha1/tenantcontrolplane_funcs.go
+++ b/api/v1alpha1/tenantcontrolplane_funcs.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"net"
 	"strconv"
+	"strings"
 
 	"github.com/pkg/errors"
 	corev1 "k8s.io/api/core/v1"
@@ -95,3 +96,17 @@ func getLoadBalancerAddress(ingress []corev1.LoadBalancerIngress) (string, error
 
 	return "", kamajierrors.MissingValidIPError{}
 }
+
+func (in *TenantControlPlane) normalizeNamespaceName() string {
+	// The dash character (-) must be replaced with an underscore, PostgreSQL is complaining about it:
+	// https://github.com/clastix/kamaji/issues/328
+	return strings.ReplaceAll(fmt.Sprintf("%s_%s", in.GetNamespace(), in.GetName()), "-", "_")
+}
+
+func (in *TenantControlPlane) GetDefaultDatastoreUsername() string {
+	return in.normalizeNamespaceName()
+}
+
+func (in *TenantControlPlane) GetDefaultDatastoreSchema() string {
+	return in.normalizeNamespaceName()
+}
diff --git a/internal/resources/datastore/datastore_storage_config.go b/internal/resources/datastore/datastore_storage_config.go
index 73e7dc2..6e4f029 100644
--- a/internal/resources/datastore/datastore_storage_config.go
+++ b/internal/resources/datastore/datastore_storage_config.go
@@ -5,7 +5,6 @@ package datastore
 
 import (
 	"context"
-	"fmt"
 
 	"github.com/google/uuid"
 	"github.com/pkg/errors"
@@ -163,8 +162,7 @@ func (r *Config) mutate(ctx context.Context, tenantControlPlane *kamajiv1alpha1.
 				// or defaulted by the defaulting webhook
 				username = []byte(tenantControlPlane.Spec.DataStoreUsername)
 			default:
-				// this can only happen on TCP creations when the webhook is not installed
-				return fmt.Errorf("cannot build datastore storage config, username must either exist in Spec or Status")
+				username = []byte(tenantControlPlane.GetDefaultDatastoreUsername())
 			}
 		}
 
@@ -180,8 +178,7 @@ func (r *Config) mutate(ctx context.Context, tenantControlPlane *kamajiv1alpha1.
 			// or defaulted by the defaulting webhook
 			dataStoreSchema = tenantControlPlane.Spec.DataStoreSchema
 		default:
-			// this can only happen on TCP creations when the webhook is not installed
-			return fmt.Errorf("cannot build datastore storage config, schema name must either exist in Spec or Status")
+			dataStoreSchema = tenantControlPlane.GetDefaultDatastoreSchema()
 		}
 
 		r.resource.Data = map[string][]byte{
diff --git a/internal/resources/datastore/datastore_storage_config_test.go b/internal/resources/datastore/datastore_storage_config_test.go
index a71383a..b81a44f 100644
--- a/internal/resources/datastore/datastore_storage_config_test.go
+++ b/internal/resources/datastore/datastore_storage_config_test.go
@@ -5,6 +5,7 @@ package datastore_test
 
 import (
 	"context"
+	"fmt"
 
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
@@ -60,10 +61,20 @@ var _ = Describe("DatastoreStorageConfig", func() {
 		}
 	})
 
-	When("TCP has neither dataStoreSchema nor dataStoreUsername defined", func() {
+	When("TCP has neither dataStoreSchema nor dataStoreUsername defined, fallback to default value", func() {
 		It("should return an error", func() {
-			_, err := resources.Handle(ctx, dsc, tcp)
-			Expect(err).To(HaveOccurred())
+			op, err := resources.Handle(ctx, dsc, tcp)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(op).To(Equal(controllerutil.OperationResultCreated))
+
+			var secrets corev1.SecretList
+			Expect(fakeClient.List(ctx, &secrets)).To(Succeed())
+			Expect(secrets.Items).To(HaveLen(1))
+
+			expectedValue := []byte(fmt.Sprintf("%s_%s", tcp.Namespace, tcp.Name))
+
+			Expect(secrets.Items[0].Data["DB_SCHEMA"]).To(Equal(expectedValue))
+			Expect(secrets.Items[0].Data["DB_USER"]).To(Equal(expectedValue))
 		})
 	})
 
diff --git a/internal/webhook/handlers/tcp_defaults.go b/internal/webhook/handlers/tcp_defaults.go
index 06fd184..7141040 100644
--- a/internal/webhook/handlers/tcp_defaults.go
+++ b/internal/webhook/handlers/tcp_defaults.go
@@ -5,9 +5,7 @@ package handlers
 
 import (
 	"context"
-	"fmt"
 	"net"
-	"strings"
 
 	"github.com/pkg/errors"
 	"gomodules.xyz/jsonpatch/v2"
@@ -73,14 +71,10 @@ func (t TenantControlPlaneDefaults) defaultUnsetFields(tcp *kamajiv1alpha1.Tenan
 	}
 
 	if len(tcp.Spec.DataStoreSchema) == 0 {
-		dss := strings.ReplaceAll(fmt.Sprintf("%s_%s", tcp.GetNamespace(), tcp.GetName()), "-", "_")
-		tcp.Spec.DataStoreSchema = dss
+		tcp.Spec.DataStoreSchema = tcp.GetDefaultDatastoreSchema()
 	}
 
 	if len(tcp.Spec.DataStoreUsername) == 0 {
-		// The dash character (-) must be replaced with an underscore, PostgreSQL is complaining about it:
-		// https://github.com/clastix/kamaji/issues/328
-		username := strings.ReplaceAll(fmt.Sprintf("%s_%s", tcp.GetNamespace(), tcp.GetName()), "-", "_")
-		tcp.Spec.DataStoreUsername = username
+		tcp.Spec.DataStoreUsername = tcp.GetDefaultDatastoreUsername()
 	}
 }