diff --git a/src/main/java/org/springframework/data/convert/ClassGeneratingEntityInstantiator.java b/src/main/java/org/springframework/data/convert/ClassGeneratingEntityInstantiator.java
index d083b0bba..025ea6f91 100644
--- a/src/main/java/org/springframework/data/convert/ClassGeneratingEntityInstantiator.java
+++ b/src/main/java/org/springframework/data/convert/ClassGeneratingEntityInstantiator.java
@@ -19,8 +19,6 @@ import static org.springframework.asm.Opcodes.*;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Modifier;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
@@ -30,6 +28,7 @@ import org.springframework.asm.ClassWriter;
 import org.springframework.asm.MethodVisitor;
 import org.springframework.asm.Opcodes;
 import org.springframework.asm.Type;
+import org.springframework.cglib.core.ReflectUtils;
 import org.springframework.data.mapping.PersistentEntity;
 import org.springframework.data.mapping.PersistentProperty;
 import org.springframework.data.mapping.PreferredConstructor;
@@ -38,7 +37,6 @@ import org.springframework.data.mapping.model.MappingInstantiationException;
 import org.springframework.data.mapping.model.ParameterValueProvider;
 import org.springframework.data.util.TypeInformation;
 import org.springframework.lang.Nullable;
-import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -139,20 +137,20 @@ public class ClassGeneratingEntityInstantiator implements EntityInstantiator {
 	 * @param entity
 	 * @return
 	 */
-	private boolean shouldUseReflectionEntityInstantiator(PersistentEntity<?, ?> entity) {
+	boolean shouldUseReflectionEntityInstantiator(PersistentEntity<?, ?> entity) {
 
 		Class<?> type = entity.getType();
 
 		if (type.isInterface() //
 				|| type.isArray() //
-				|| !Modifier.isPublic(type.getModifiers()) //
+				|| Modifier.isPrivate(type.getModifiers()) //
 				|| (type.isMemberClass() && !Modifier.isStatic(type.getModifiers())) //
 				|| ClassUtils.isCglibProxyClass(type)) { //
 			return true;
 		}
 
 		PreferredConstructor<?, ?> persistenceConstructor = entity.getPersistenceConstructor();
-		if (persistenceConstructor == null || !Modifier.isPublic(persistenceConstructor.getConstructor().getModifiers())) {
+		if (persistenceConstructor == null || Modifier.isPrivate(persistenceConstructor.getConstructor().getModifiers())) {
 			return true;
 		}
 
@@ -299,6 +297,7 @@ public class ClassGeneratingEntityInstantiator implements EntityInstantiator {
 	 * </pre>
 	 *
 	 * @author Thomas Darimont
+	 * @author Mark Paluch
 	 */
 	static class ObjectInstantiatorClassGenerator {
 
@@ -310,13 +309,6 @@ public class ClassGeneratingEntityInstantiator implements EntityInstantiator {
 		private static final String[] IMPLEMENTED_INTERFACES = new String[] {
 				Type.getInternalName(ObjectInstantiator.class) };
 
-		private final ByteArrayClassLoader classLoader;
-
-		ObjectInstantiatorClassGenerator() {
-
-			this.classLoader = AccessController.doPrivileged(
-					(PrivilegedAction<ByteArrayClassLoader>) () -> new ByteArrayClassLoader(ClassUtils.getDefaultClassLoader()));
-		}
 
 		/**
 		 * Generate a new class for the given {@link PersistentEntity}.
@@ -331,7 +323,13 @@ public class ClassGeneratingEntityInstantiator implements EntityInstantiator {
 			String className = generateClassName(entity);
 			byte[] bytecode = generateBytecode(className, entity, constructor);
 
-			return classLoader.loadClass(className, bytecode);
+			Class<?> type = entity.getType();
+
+			try {
+				return ReflectUtils.defineClass(className, bytecode, type.getClassLoader(), type.getProtectionDomain());
+			} catch (Exception e) {
+				throw new IllegalStateException(e);
+			}
 		}
 
 		/**
@@ -523,39 +521,5 @@ public class ClassGeneratingEntityInstantiator implements EntityInstantiator {
 					throw new IllegalArgumentException("Unboxing should not be attempted for descriptor '" + ch + "'");
 			}
 		}
-
-		/**
-		 * A {@link ClassLoader} that can load classes from {@code byte[]} representations.
-		 *
-		 * @author Thomas Darimont
-		 */
-		private class ByteArrayClassLoader extends ClassLoader {
-
-			public ByteArrayClassLoader(@Nullable ClassLoader parent) {
-				super(parent);
-			}
-
-			/**
-			 * Tries to load a class given {@code byte[]}.
-			 *
-			 * @param name must not be {@literal null}
-			 * @param bytes must not be {@literal null}
-			 * @return
-			 */
-			public Class<?> loadClass(String name, byte[] bytes) {
-
-				Assert.notNull(name, "name must not be null");
-				Assert.notNull(bytes, "bytes must not be null");
-
-				try {
-					Class<?> clazz = findClass(name);
-					if (clazz != null) {
-						return clazz;
-					}
-				} catch (ClassNotFoundException ignore) {}
-
-				return defineClass(name, bytes, 0, bytes.length);
-			}
-		}
 	}
 }
diff --git a/src/test/java/org/springframework/data/convert/ClassGeneratingEntityInstantiatorUnitTests.java b/src/test/java/org/springframework/data/convert/ClassGeneratingEntityInstantiatorUnitTests.java
index 4de3b357e..1e05d5047 100755
--- a/src/test/java/org/springframework/data/convert/ClassGeneratingEntityInstantiatorUnitTests.java
+++ b/src/test/java/org/springframework/data/convert/ClassGeneratingEntityInstantiatorUnitTests.java
@@ -303,6 +303,66 @@ public class ClassGeneratingEntityInstantiatorUnitTests<P extends PersistentProp
 		});
 	}
 
+	@Test // DATACMNS-1373
+	public void shouldInstantiateProtectedInnerClass() {
+
+		prepareMocks(ProtectedInnerClass.class);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isFalse();
+		assertThat(this.instance.createInstance(entity, provider)).isInstanceOf(ProtectedInnerClass.class);
+	}
+
+	@Test // DATACMNS-1373
+	public void shouldInstantiatePackagePrivateInnerClass() {
+
+		prepareMocks(PackagePrivateInnerClass.class);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isFalse();
+		assertThat(this.instance.createInstance(entity, provider)).isInstanceOf(PackagePrivateInnerClass.class);
+	}
+
+	@Test // DATACMNS-1373
+	public void shouldNotInstantiatePrivateInnerClass() {
+
+		prepareMocks(PrivateInnerClass.class);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isTrue();
+	}
+
+	@Test // DATACMNS-1373
+	public void shouldInstantiateClassWithPackagePrivateConstructor() {
+
+		prepareMocks(ClassWithPackagePrivateConstructor.class);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isFalse();
+		assertThat(this.instance.createInstance(entity, provider)).isInstanceOf(ClassWithPackagePrivateConstructor.class);
+	}
+
+	@Test // DATACMNS-1373
+	public void shouldInstantiateClassInDefaultPackage() throws ClassNotFoundException {
+
+		Class<?> typeInDefaultPackage = Class.forName("TypeInDefaultPackage");
+		prepareMocks(typeInDefaultPackage);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isFalse();
+		assertThat(this.instance.createInstance(entity, provider)).isInstanceOf(typeInDefaultPackage);
+	}
+
+	@Test // DATACMNS-1373
+	public void shouldNotInstantiateClassWithPrivateConstructor() {
+
+		prepareMocks(ClassWithPrivateConstructor.class);
+
+		assertThat(this.instance.shouldUseReflectionEntityInstantiator(entity)).isTrue();
+	}
+
+	private void prepareMocks(Class<?> type) {
+
+		doReturn(type).when(entity).getType();
+		doReturn(PreferredConstructorDiscoverer.discover(type))//
+				.when(entity).getPersistenceConstructor();
+	}
+
 	static class Foo {
 
 		Foo(String foo) {
@@ -424,4 +484,21 @@ public class ClassGeneratingEntityInstantiatorUnitTests<P extends PersistentProp
 			this.param7 = param7;
 		}
 	}
+
+	protected static class ProtectedInnerClass {}
+
+	static class PackagePrivateInnerClass {}
+
+	private static class PrivateInnerClass {}
+
+	static class ClassWithPrivateConstructor {
+
+		private ClassWithPrivateConstructor() {}
+	}
+
+	static class ClassWithPackagePrivateConstructor {
+
+		ClassWithPackagePrivateConstructor() {}
+	}
+
 }