diff --git a/spring-aop/src/test/kotlin/org/springframework/aop/framework/CglibAopProxyKotlinTests.kt b/spring-aop/src/test/kotlin/org/springframework/aop/framework/CglibAopProxyKotlinTests.kt
index 10e632abd3..0489d68bb0 100644
--- a/spring-aop/src/test/kotlin/org/springframework/aop/framework/CglibAopProxyKotlinTests.kt
+++ b/spring-aop/src/test/kotlin/org/springframework/aop/framework/CglibAopProxyKotlinTests.kt
@@ -19,6 +19,7 @@ package org.springframework.aop.framework
 import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.Assertions.assertThatThrownBy
 import org.junit.jupiter.api.Test
+import java.time.LocalDateTime
 
 /**
  * Tests for Kotlin support in [CglibAopProxy].
@@ -48,6 +49,13 @@ class CglibAopProxyKotlinTests {
 		assertThatThrownBy { proxy.checkedException() }.isInstanceOf(CheckedException::class.java)
 	}
 
+	@Test // gh-35487
+	fun jvmDefault() {
+		val proxyFactory = ProxyFactory()
+		proxyFactory.setTarget(AddressRepo())
+		proxyFactory.proxy
+	}
+
 
 	open class MyKotlinBean {
 
@@ -63,4 +71,24 @@ class CglibAopProxyKotlinTests {
 	}
 
 	class CheckedException() : Exception()
+
+	open class AddressRepo(): CrudRepo<Address, Int>
+
+	interface CrudRepo<E : Any, ID : Any> {
+		fun save(e: E): E {
+			return e
+		}
+		fun delete(id: ID): Long {
+			return 0L
+		}
+	}
+
+	data class Address(
+		val id: Int = 0,
+		val street: String,
+		val version: Int = 0,
+		val createdAt: LocalDateTime? = null,
+		val updatedAt: LocalDateTime? = null,
+	)
+
 }
diff --git a/spring-core/src/main/java/org/springframework/cglib/proxy/Enhancer.java b/spring-core/src/main/java/org/springframework/cglib/proxy/Enhancer.java
index 3acd2fd69f..f9f5275cac 100644
--- a/spring-core/src/main/java/org/springframework/cglib/proxy/Enhancer.java
+++ b/spring-core/src/main/java/org/springframework/cglib/proxy/Enhancer.java
@@ -1282,29 +1282,32 @@ public class Enhancer extends AbstractClassGenerator {
 				Signature bridgeTarget = (Signature) bridgeToTarget.get(method.getSignature());
 				if (bridgeTarget != null) {
 					// checkcast each argument against the target's argument types
-					for (int i = 0; i < bridgeTarget.getArgumentTypes().length; i++) {
+					Type[] argTypes = method.getSignature().getArgumentTypes();
+					Type[] targetTypes = bridgeTarget.getArgumentTypes();
+					for (int i = 0; i < targetTypes.length; i++) {
 						e.load_arg(i);
-						Type target = bridgeTarget.getArgumentTypes()[i];
-						if (!target.equals(method.getSignature().getArgumentTypes()[i])) {
+						Type argType = argTypes[i];
+						Type target = targetTypes[i];
+						if (!target.equals(argType)) {
+							if (!TypeUtils.isPrimitive(target)) {
+								e.box(argType);
+							}
 							e.checkcast(target);
 						}
 					}
 
 					e.invoke_virtual_this(bridgeTarget);
 
+					// Not necessary to cast if the target & bridge have the same return type.
 					Type retType = method.getSignature().getReturnType();
-					// Not necessary to cast if the target & bridge have
-					// the same return type.
-					// (This conveniently includes void and primitive types,
-					// which would fail if casted.  It's not possible to
-					// covariant from boxed to unbox (or vice versa), so no having
-					// to box/unbox for bridges).
-					// TODO: It also isn't necessary to checkcast if the return is
-					// assignable from the target.  (This would happen if a subclass
-					// used covariant returns to narrow the return type within a bridge
-					// method.)
-					if (!retType.equals(bridgeTarget.getReturnType())) {
-						e.checkcast(retType);
+					Type target = bridgeTarget.getReturnType();
+					if (!target.equals(retType)) {
+						if (!TypeUtils.isPrimitive(target)) {
+							e.unbox(retType);
+						}
+						else {
+							e.checkcast(retType);
+						}
 					}
 				}
 				else {