diff --git a/Sources/ManagedModelMacros/ModelMacro/GenerateInitializers.swift b/Sources/ManagedModelMacros/ModelMacro/GenerateInitializers.swift
index db4ced2..5f8272f 100644
--- a/Sources/ManagedModelMacros/ModelMacro/GenerateInitializers.swift
+++ b/Sources/ManagedModelMacros/ModelMacro/GenerateInitializers.swift
@@ -42,11 +42,8 @@ extension ModelMacro {
       /// - Parameters:
       //    - entity:  An `NSEntityDescription` describing the object.
       //    - context: An `NSManagedObjectContext` the object should be inserted into.
-      @available(*, deprecated, renamed: "init(context:)",
-                 message: "Use `init(context:)` or `init()` instead.")
       \(raw: access)override init(entity: CoreData.NSEntityDescription, insertInto context: NSManagedObjectContext?)
       {
-        assert(entity === Self._$entity, "Attempt to initialize PersistentModel w/ different entity?")
         super.init(entity: entity, insertInto: context)
       }
       """
@@ -67,7 +64,7 @@ extension ModelMacro {
       /// - Parameters:
       //    - context: An `NSManagedObjectContext` the object should be inserted into.
       \(raw: access)init(context: CoreData.NSManagedObjectContext?) {
-        super.init(entity: Self._$entity, insertInto: context)
+        super.init(entity: Self.entity(), insertInto: context)
       }
       """
     )
@@ -78,7 +75,7 @@ extension ModelMacro {
         /// Initialize a `\(modelClassName)` object w/o inserting it into a
         /// context.
         \(raw: access)init() {
-          super.init(entity: Self._$entity, insertInto: nil)
+          super.init(entity: Self.entity(), insertInto: nil)
         }
         """
       )
diff --git a/Sources/ManagedModelMacros/ModelMacro/ModelMembers.swift b/Sources/ManagedModelMacros/ModelMacro/ModelMembers.swift
index cf8ea79..3eba04e 100644
--- a/Sources/ManagedModelMacros/ModelMacro/ModelMembers.swift
+++ b/Sources/ManagedModelMacros/ModelMacro/ModelMembers.swift
@@ -14,8 +14,6 @@ import SwiftDiagnostics
  * @attached(member, names: // Those are the names we add
  *   named(init),           // Initializers.
  *   named(schemaMetadata), // The metadata.
- *   named(entity),         // Override the `entity()` function.
- *   named(_$entity),       // The cached the Entity
  *   named(_$originalName),
  *   named(_$hashModifier)
  * )
@@ -55,17 +53,6 @@ extension ModelMacro: MemberMacro { // @attached(member, names:...)
     )
     newMembers.append(DeclSyntax(metadata))
 
-    if classDecl.findFunctionWithName("entity", isStaticOrClass: true,
-                                      parameterCount: 0) == nil
-    {
-      newMembers.append(
-        """
-        /// Returns the `NSEntityDescription` associated w/ the `PersistentModel`.
-        \(raw: access)override class func entity() -> NSEntityDescription { _$entity }
-        """
-      )
-    }
-    
     // TODO: Lookup `originalName` parameter in `macroNode`
     newMembers.append(
       """
@@ -77,15 +64,6 @@ extension ModelMacro: MemberMacro { // @attached(member, names:...)
       \(raw: access)static let _$hashModifier : String? = nil
       """
     )
-
-    newMembers.append(
-      """
-      /// The shared `NSEntityDescription` for the `PersistentModel`.
-      /// Never modify the referred object!
-      \(raw: access)static let _$entity =
-        ManagedModels.SchemaBuilder.shared._entity(for: \(modelClassName).self)
-      """
-    )
     
     return newMembers
   }
diff --git a/Sources/ManagedModels/ModelMacroDefinition.swift b/Sources/ManagedModels/ModelMacroDefinition.swift
index 09c4d4b..4a762f9 100644
--- a/Sources/ManagedModels/ModelMacroDefinition.swift
+++ b/Sources/ManagedModels/ModelMacroDefinition.swift
@@ -81,8 +81,6 @@ public macro _PersistedProperty() =
 @attached(member, names: // Those are the names we add
   named(init),           // Initializers.
   named(schemaMetadata), // The metadata.
-  named(entity),         // Override the `entity()` function.
-  named(_$entity),       // The cached the Entity
   named(_$originalName),
   named(_$hashModifier)
 )
diff --git a/Sources/ManagedModels/PersistentModel/PersistentModel+KVC.swift b/Sources/ManagedModels/PersistentModel/PersistentModel+KVC.swift
index 0ae9630..4bb2bed 100644
--- a/Sources/ManagedModels/PersistentModel/PersistentModel+KVC.swift
+++ b/Sources/ManagedModels/PersistentModel/PersistentModel+KVC.swift
@@ -120,10 +120,6 @@ public extension PersistentModel {
   func _setOptionalToOneValue<T>(forKey key: String, to model: T?)
     where T: PersistentModel
   {
-    #if DEBUG
-    let relship = Self._$entity.relationshipsByName[key]!
-    assert(!relship.isToMany, "relship: \(relship)")
-    #endif
     if let model {
       if model.modelContext != self.modelContext {
         if let otherCtx = model.modelContext, self.modelContext == nil {
diff --git a/Sources/ManagedModels/PersistentModel/PersistentModel.swift b/Sources/ManagedModels/PersistentModel/PersistentModel.swift
index cafa6ec..9360666 100644
--- a/Sources/ManagedModels/PersistentModel/PersistentModel.swift
+++ b/Sources/ManagedModels/PersistentModel/PersistentModel.swift
@@ -19,16 +19,6 @@ public protocol PersistentModel: NSManagedObject, Hashable, Identifiable {
    */
   static var schemaMetadata : [ NSManagedObjectModel.PropertyMetadata ] { get }
   
-  /**
-   * Reflection data for the model.
-   *
-   * This is considered private, use a Schema to access entities, and NEVER
-   * modify the schema objects after they got setup.
-   *
-   * API DIFF: SwiftData doesn't have that, always builds dynamically.
-   */
-  static var _$entity : NSEntityDescription { get }
-    // Why have that? Cheap cache.
 
   /// The `renamingIdentifier` of the model.
   static var _$originalName : String? { get }
@@ -55,16 +45,13 @@ extension PersistentModel {
   public static var schemaMetadata : [ NSManagedObjectModel.PropertyMetadata ] {
     fatalError("Subclass needs to implement `schemaMetadata`")
   }
-  
-  @inlinable
-  public static var _$entity : NSEntityDescription { self.entity() }
 }
 
 public extension PersistentModel {
 
   @inlinable
   static func fetchRequest() -> NSFetchRequest<Self> {
-    NSFetchRequest<Self>(entityName: _$entity.name ?? NSStringFromClass(self))
+    NSFetchRequest<Self>(entityName: _typeName(Self.self, qualified: false))
   }
   
   @inlinable
diff --git a/Sources/ManagedModels/SchemaCompatibility/CoreDataPrimitiveValue.swift b/Sources/ManagedModels/SchemaCompatibility/CoreDataPrimitiveValue.swift
index d79f16e..1228903 100644
--- a/Sources/ManagedModels/SchemaCompatibility/CoreDataPrimitiveValue.swift
+++ b/Sources/ManagedModels/SchemaCompatibility/CoreDataPrimitiveValue.swift
@@ -9,7 +9,7 @@ public extension CoreData.NSAttributeDescription {
   struct TypeConfiguration {
     let attributeType           : NSAttributeType
     let isOptional              : Bool
-    let attributeValueClassName : String
+    let attributeValueClassName : String?
   }
 }
 
@@ -37,35 +37,35 @@ extension Int: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .integer64AttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 extension Int16: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .integer16AttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 extension Int32: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .integer32AttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 extension Int64: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .integer64AttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 extension Int8: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .integer16AttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 
@@ -91,7 +91,7 @@ extension String: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .stringAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSString"
+    attributeValueClassName : nil
   )
 }
 
@@ -99,7 +99,7 @@ extension Bool: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .booleanAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 
@@ -107,14 +107,14 @@ extension Double: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .doubleAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 extension Float: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .floatAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSNumber"
+    attributeValueClassName : nil
   )
 }
 
@@ -124,7 +124,7 @@ extension Date: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .dateAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSDate"
+    attributeValueClassName : nil
   )
 }
 
@@ -132,7 +132,7 @@ extension Data: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .binaryDataAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSDate"
+    attributeValueClassName : nil
   )
 }
 
@@ -140,7 +140,7 @@ extension Decimal: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .decimalAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSDecimalNumber"
+    attributeValueClassName : nil
   )
 }
 
@@ -148,7 +148,7 @@ extension UUID: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .UUIDAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSUUID"
+    attributeValueClassName : nil
   )
 }
 
@@ -156,6 +156,6 @@ extension URL: CoreDataPrimitiveValue {
   public static let coreDataValue = NSAttributeDescription.TypeConfiguration(
     attributeType           : .URIAttributeType,
     isOptional              : false,
-    attributeValueClassName : "NSURL"
+    attributeValueClassName : nil
   )
 }
diff --git a/Sources/ManagedModels/SchemaCompatibility/NSAttributeDescription+Data.swift b/Sources/ManagedModels/SchemaCompatibility/NSAttributeDescription+Data.swift
index 4aec422..141ad3a 100644
--- a/Sources/ManagedModels/SchemaCompatibility/NSAttributeDescription+Data.swift
+++ b/Sources/ManagedModels/SchemaCompatibility/NSAttributeDescription+Data.swift
@@ -42,7 +42,9 @@ extension CoreData.NSAttributeDescription: SchemaProperty {
         let config = primitiveType.coreDataValue
         self.attributeType           = config.attributeType
         self.isOptional              = config.isOptional
-        self.attributeValueClassName = config.attributeValueClassName
+        if let newClassName = config.attributeValueClassName {
+          self.attributeValueClassName = newClassName
+        }
         return
       }
       
@@ -55,7 +57,9 @@ extension CoreData.NSAttributeDescription: SchemaProperty {
             let config = primitiveType.coreDataValue
             self.attributeType           = config.attributeType
             self.isOptional              = config.isOptional
-            self.attributeValueClassName = config.attributeValueClassName
+            if let newClassName = config.attributeValueClassName {
+              self.attributeValueClassName = newClassName
+            }
             return true
           }
           else {
diff --git a/Sources/ManagedModels/SchemaCompatibility/NSManagedObjectModel+Data.swift b/Sources/ManagedModels/SchemaCompatibility/NSManagedObjectModel+Data.swift
index c395e67..d42b2c4 100644
--- a/Sources/ManagedModels/SchemaCompatibility/NSManagedObjectModel+Data.swift
+++ b/Sources/ManagedModels/SchemaCompatibility/NSManagedObjectModel+Data.swift
@@ -11,12 +11,6 @@ public extension NSManagedObjectModel {
   // - encodingVersion
   // - version
   
-  @available(*, deprecated, renamed: "model(for:)", message:
-    """
-    Entities can only be used in one NSManagedObjectModel, use the `model(for:)`
-    static function to get access to s ahred, cached model.
-    """
-  )
   @inlinable
   convenience init(_ entities: NSEntityDescription...,
                    version: Schema.Version = Version(1, 0, 0))
@@ -25,25 +19,13 @@ public extension NSManagedObjectModel {
     self.entities = entities
   }
   
-  @available(*, deprecated, renamed: "model(for:)", message:
-    """
-    Entities can only be used in one NSManagedObjectModel, use the `model(for:)`
-    static function to get access to s ahred, cached model.
-    """
-  )
   convenience init(_ types: [ any PersistentModel.Type ],
                    version: Schema.Version = Version(1, 0, 0))
   {
     self.init()
-    self.entities = SchemaBuilder.shared.lookupAllEntities(for: types)
+    self.entities = SchemaBuilder().lookupAllEntities(for: types)
   }
   
-  @available(*, deprecated, renamed: "model(for:)", message:
-    """
-    Entities can only be used in one NSManagedObjectModel, use the `model(for:)`
-    static function to get access to s ahred, cached model.
-    """
-  )
   @inlinable
   convenience init(versionedSchema: any VersionedSchema.Type) {
     self.init(versionedSchema.models,
@@ -56,9 +38,11 @@ public extension NSManagedObjectModel {
 
 private let lock = NSLock()
 private var map = [ Set<ObjectIdentifier> : NSManagedObjectModel ]()
+private let sharedBuilder = SchemaBuilder()
 
 public extension NSManagedObjectModel {
   
+  /// A cached version of the initializer.
   static func model(for versionedSchema: VersionedSchema.Type) 
               -> NSManagedObjectModel
   {
@@ -86,7 +70,7 @@ public extension NSManagedObjectModel {
     if let cachedMOM { mom = cachedMOM }
     else {
       mom = NSManagedObjectModel()
-      mom.entities = SchemaBuilder.shared.lookupAllEntities(for: types)
+      mom.entities = sharedBuilder.lookupAllEntities(for: types)
       map[typeIDs] = mom
     }
     lock.unlock()
diff --git a/Sources/ManagedModels/SchemaGeneration/SchemaBuilder.swift b/Sources/ManagedModels/SchemaGeneration/SchemaBuilder.swift
index c5e0ff5..dace94a 100644
--- a/Sources/ManagedModels/SchemaGeneration/SchemaBuilder.swift
+++ b/Sources/ManagedModels/SchemaGeneration/SchemaBuilder.swift
@@ -27,17 +27,11 @@ import CoreData
  */
 public final class SchemaBuilder {
   // Notes:
-  // - this MUST NOT call `.entity` on the model! might recurse w/ lock, this
+  // - this MUST NOT call `.entity()` on the model! might recurse w/ lock, this
   //   object is the authority!
   // - there can be multiple entities that use the same name, this spans the
   //   whole type system. E.g. when versioned schemas are used.
-  
-  /**
-   * A shared SchemaBuilder that caches `NSEntityDescription` values for
-   * ``PersistentModel`` `NSManagedObject`'s.
-   */
-  public static let shared = SchemaBuilder()
-  
+    
   private let lock = NSLock() // TODO: use better lock :-)
   
   /// ObjectIdentifier of PersistentModel type to the associated schema.
diff --git a/Tests/ManagedModelTests/BasicModelTests.swift b/Tests/ManagedModelTests/BasicModelTests.swift
index 90f3fb0..ee8c382 100644
--- a/Tests/ManagedModelTests/BasicModelTests.swift
+++ b/Tests/ManagedModelTests/BasicModelTests.swift
@@ -16,7 +16,6 @@ final class BasicModelTests: XCTestCase {
   
   func testEntityName() throws {
     let addressType = Fixtures.PersonAddressSchema.Address.self
-    XCTAssertEqual(addressType._$entity.name, "Address")
     XCTAssertEqual(addressType.entity().name, "Address")
   }
 
diff --git a/Tests/ManagedModelTests/CoreDataAssumptionsTests.swift b/Tests/ManagedModelTests/CoreDataAssumptionsTests.swift
index f1783f6..3da87a0 100644
--- a/Tests/ManagedModelTests/CoreDataAssumptionsTests.swift
+++ b/Tests/ManagedModelTests/CoreDataAssumptionsTests.swift
@@ -20,9 +20,9 @@ final class CoreDataAssumptionsTests: XCTestCase {
     let relationship = NSRelationshipDescription()
     relationship.name = "addresses"
     //relationship.destinationEntity =
-    //  Fixtures.PersonAddressSchema.Address._$entity
+    //  Fixtures.PersonAddressSchema.Address.entity()
     //relationship.inverseRelationship =
-    //  Fixtures.PersonAddressSchema.Address._$entity.relationshipsByName["person"]
+    //  Fixtures.PersonAddressSchema.Address.entity().relationshipsByName["person"]
     
     // This just seems to be the default.
     XCTAssertTrue(relationship.isToMany)
@@ -32,9 +32,10 @@ final class CoreDataAssumptionsTests: XCTestCase {
     let relationship = NSRelationshipDescription()
     relationship.name     = "person"
     relationship.maxCount = 1 // toOne marker!
+    #if false // old
     relationship.destinationEntity =
-      Fixtures.PersonAddressSchema.Person._$entity
-    // Yes! This does not work at this point.
+      Fixtures.PersonAddressSchema.Person.entity()
+    #endif
     XCTAssertFalse(relationship.isToMany)
   }
   
diff --git a/Tests/ManagedModelTests/SchemaGenerationTests.swift b/Tests/ManagedModelTests/SchemaGenerationTests.swift
index 05e1532..4ff7919 100644
--- a/Tests/ManagedModelTests/SchemaGenerationTests.swift
+++ b/Tests/ManagedModelTests/SchemaGenerationTests.swift
@@ -224,7 +224,34 @@ final class SchemaGenerationTests: XCTestCase {
       XCTAssertEqual(address.attributes.count, 2)
     }
   }
-  
+
+  func testDuplicateMOMGeneration() throws {
+    try autoreleasepool {
+      let model1 = NSManagedObjectModel([
+        Fixtures.PersonAddressSchema.Person.self
+      ])
+      XCTAssertEqual(model1.entities.count, 2)
+      
+      let address = try XCTUnwrap(
+        model1.entities.first(where: { $0.name == "Address" })
+      )
+      XCTAssertEqual(address.attributes.count, 2)
+    }
+
+    // second run
+    try autoreleasepool {
+      let model2 = NSManagedObjectModel([
+        Fixtures.PersonAddressSchema.Person.self
+      ])
+      XCTAssertEqual(model2.entities.count, 2)
+      
+      let address = try XCTUnwrap(
+        model2.entities.first(where: { $0.name == "Address" })
+      )
+      XCTAssertEqual(address.attributes.count, 2)
+    }
+  }
+
   func testOptionalBackRef() throws {
     let cache  = SchemaBuilder()
     let schema = NSManagedObjectModel(
diff --git a/Tests/ManagedModelTests/Schemas/ExpandedPersonAddressSchema.swift b/Tests/ManagedModelTests/Schemas/ExpandedPersonAddressSchema.swift
index d3581f6..a6c442d 100644
--- a/Tests/ManagedModelTests/Schemas/ExpandedPersonAddressSchema.swift
+++ b/Tests/ManagedModelTests/Schemas/ExpandedPersonAddressSchema.swift
@@ -31,7 +31,7 @@ extension Fixtures {
       
       init(firstname: String, lastname: String, addresses: [ Address ]) {
         // Note: Could do Self.entity!
-        super.init(entity: Self._$entity, insertInto: nil)
+        super.init(entity: Self.entity(), insertInto: nil)
         self.firstname = firstname
         self.lastname  = lastname
         self.addresses = addresses
@@ -42,7 +42,6 @@ extension Fixtures {
         .init(name: "lastname"  , keypath: \Person.lastname),
         .init(name: "addresses" , keypath: \Person.addresses)
       ]
-      public static let _$entity = SchemaBuilder.shared._entity(for: Person.self)
       public static let _$originalName : String? = nil
       public static let _$hashModifier : String? = nil
     }
@@ -54,7 +53,7 @@ extension Fixtures {
       @NSManaged var person     : Person
       
       init(street: String, appartment: String? = nil, person: Person) {
-        super.init(entity: Self._$entity, insertInto: nil)
+        super.init(entity: Self.entity(), insertInto: nil)
         self.street     = street
         self.appartment = appartment
         self.person     = person
@@ -65,7 +64,6 @@ extension Fixtures {
         .init(name: "appartment" , keypath: \Address.appartment),
         .init(name: "person"     , keypath: \Address.person)
       ]
-      public static let _$entity = SchemaBuilder.shared._entity(for: Address.self)
       public static let _$originalName : String? = nil
       public static let _$hashModifier : String? = nil
     }
diff --git a/Tests/ManagedModelTests/Schemas/PersonAddressSchemaNoInverse.swift b/Tests/ManagedModelTests/Schemas/PersonAddressSchemaNoInverse.swift
index efff698..07d9e7b 100644
--- a/Tests/ManagedModelTests/Schemas/PersonAddressSchemaNoInverse.swift
+++ b/Tests/ManagedModelTests/Schemas/PersonAddressSchemaNoInverse.swift
@@ -24,7 +24,7 @@ extension Fixtures {
       var addresses : [ Address ]
       
       init(firstname: String, lastname: String, addresses: [ Address ]) {
-        super.init(entity: Self._$entity, insertInto: nil)
+        super.init(entity: Self.entity(), insertInto: nil)
         self.firstname = firstname
         self.lastname  = lastname
         self.addresses = addresses