diff --git a/audit/api/api_common.go b/audit/api/api_common.go
index 15f6d68..97fbed2 100644
--- a/audit/api/api_common.go
+++ b/audit/api/api_common.go
@@ -84,7 +84,7 @@ func validateAndSerializePartially(
 	}
 
 	// Check that provided identifier type is supported
-	if err := IsSupportedSingularType(routableIdentifier.Type); err != nil {
+	if err := routableIdentifier.Type.IsSupportedType(); err != nil {
 		if errors.Is(err, ErrUnknownSingularType) {
 			return nil, ErrUnsupportedRoutableType
 		}
@@ -149,7 +149,7 @@ func send(
 	}
 
 	// Check that provided identifier type is supported
-	if err := IsSupportedSingularType(routableIdentifier.Type); err != nil {
+	if err := routableIdentifier.Type.IsSupportedType(); err != nil {
 		if errors.Is(err, ErrUnknownSingularType) {
 			return ErrUnsupportedRoutableType
 		}
@@ -196,7 +196,7 @@ func isSystemIdentifier(identifier *RoutableIdentifier) bool {
 func areIdentifiersIdentical(routableIdentifier *RoutableIdentifier, logName string) error {
 	dataType, identifier := getTypeAndIdentifierFromString(logName)
 	pluralType := AsPluralType(dataType)
-	singularType, err := SingularTypeFromPlural(pluralType)
+	singularType, err := pluralType.AsSingularType()
 	if err != nil {
 		return err
 	}
diff --git a/audit/api/api_routable_types.go b/audit/api/api_routable_types.go
index c8f90f5..6b99ce3 100644
--- a/audit/api/api_routable_types.go
+++ b/audit/api/api_routable_types.go
@@ -6,19 +6,47 @@ const (
 	SingularTypeFolder       SingularType = "folder"
 	SingularTypeProject      SingularType = "project"
 
-	PluralTypeTest         PluralType = "test"
 	PluralTypeSystem       PluralType = "system"
 	PluralTypeOrganization PluralType = "organizations"
 	PluralTypeFolder       PluralType = "folders"
 	PluralTypeProject      PluralType = "projects"
 )
 
+func (t SingularType) AsPluralType() (PluralType, error) {
+	switch t {
+	case SingularTypeSystem:
+		return PluralTypeSystem, nil
+	case SingularTypeOrganization:
+		return PluralTypeOrganization, nil
+	case SingularTypeFolder:
+		return PluralTypeFolder, nil
+	case SingularTypeProject:
+		return PluralTypeProject, nil
+	}
+	return "unknown", ErrUnknownSingularType
+}
+
 func AsPluralType(value string) PluralType {
 	return PluralType(value)
 }
 
-func SingularTypeFromPlural(pluralType PluralType) (SingularType, error) {
-	switch pluralType {
+func (t PluralType) IsSupportedType() error {
+	switch t {
+	case PluralTypeOrganization:
+		fallthrough
+	case PluralTypeFolder:
+		fallthrough
+	case PluralTypeProject:
+		fallthrough
+	case PluralTypeSystem:
+		return nil
+	default:
+		return ErrUnknownSingularType
+	}
+}
+
+func (t PluralType) AsSingularType() (SingularType, error) {
+	switch t {
 	case PluralTypeOrganization:
 		return SingularTypeOrganization, nil
 	case PluralTypeFolder:
@@ -28,7 +56,7 @@ func SingularTypeFromPlural(pluralType PluralType) (SingularType, error) {
 	case PluralTypeSystem:
 		return SingularTypeSystem, nil
 	default:
-		return "", ErrUnknownPluralType
+		return "unknown", ErrUnknownPluralType
 	}
 }
 
@@ -36,8 +64,8 @@ func AsSingularType(value string) SingularType {
 	return SingularType(value)
 }
 
-func IsSupportedSingularType(singularType SingularType) error {
-	switch singularType {
+func (t SingularType) IsSupportedType() error {
+	switch t {
 	case SingularTypeOrganization:
 		fallthrough
 	case SingularTypeFolder:
@@ -48,6 +76,5 @@ func IsSupportedSingularType(singularType SingularType) error {
 		return nil
 	default:
 		return ErrUnknownSingularType
-
 	}
 }