diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanDefinitionValidator.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanDefinitionValidator.java
index c5c4653c2c3..413fedb99a0 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanDefinitionValidator.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanDefinitionValidator.java
@@ -40,13 +40,17 @@ class ConfigurationPropertiesBeanDefinitionValidator implements BeanFactoryPostP
 	@Override
 	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
 		for (String beanName : beanFactory.getBeanDefinitionNames()) {
-			BeanDefinition definition = beanFactory.getBeanDefinition(beanName);
-			if (!(definition instanceof ConfigurationPropertiesValueObjectBeanDefinition)) {
+			if (!(beanFactory.containsSingleton(beanName) || isValueObjectBeanDefinition(beanFactory, beanName))) {
 				validate(beanFactory, beanName);
 			}
 		}
 	}
 
+	private boolean isValueObjectBeanDefinition(ConfigurableListableBeanFactory beanFactory, String beanName) {
+		BeanDefinition definition = beanFactory.getBeanDefinition(beanName);
+		return (definition instanceof ConfigurationPropertiesValueObjectBeanDefinition);
+	}
+
 	@Override
 	public int getOrder() {
 		return Ordered.LOWEST_PRECEDENCE;
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
index 9c3ee77a5a3..729b70b2163 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java
@@ -44,8 +44,11 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.beans.factory.annotation.Value;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.GenericBeanDefinition;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.boot.context.properties.bind.BindException;
 import org.springframework.boot.context.properties.bind.DefaultValue;
 import org.springframework.boot.context.properties.bind.validation.BindValidationException;
@@ -895,6 +898,15 @@ class ConfigurationPropertiesTests {
 		assertThat(bean.getNested().getAge()).isEqualTo(10);
 	}
 
+	@Test // gh-18652
+	void loadWhenBeanFactoryContainsSingletonForConstructorBindingTypeShouldNotFail() {
+		ConfigurableListableBeanFactory beanFactory = this.context.getBeanFactory();
+		((BeanDefinitionRegistry) beanFactory).registerBeanDefinition("test",
+				new RootBeanDefinition(ConstructorParameterProperties.class));
+		beanFactory.registerSingleton("test", new ConstructorParameterProperties("bar", 5));
+		load(TestConfiguration.class);
+	}
+
 	private AnnotationConfigApplicationContext load(Class<?> configuration, String... inlinedProperties) {
 		return load(new Class<?>[] { configuration }, inlinedProperties);
 	}
@@ -921,6 +933,12 @@ class ConfigurationPropertiesTests {
 		this.context = new AnnotationConfigApplicationContext();
 	}
 
+	@Configuration(proxyBeanMethods = false)
+	@EnableConfigurationProperties
+	static class TestConfiguration {
+
+	}
+
 	@Configuration(proxyBeanMethods = false)
 	@EnableConfigurationProperties(BasicProperties.class)
 	static class BasicConfiguration {
diff --git a/spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/KotlinConfigurationPropertiesTests.kt b/spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/KotlinConfigurationPropertiesTests.kt
new file mode 100644
index 00000000000..db95e2346ca
--- /dev/null
+++ b/spring-boot-project/spring-boot/src/test/kotlin/org/springframework/boot/context/properties/KotlinConfigurationPropertiesTests.kt
@@ -0,0 +1,40 @@
+package org.springframework.boot.context.properties
+
+import org.junit.jupiter.api.Test
+import org.springframework.beans.factory.support.BeanDefinitionRegistry
+import org.springframework.beans.factory.support.RootBeanDefinition
+import org.springframework.context.annotation.AnnotationConfigApplicationContext
+import org.springframework.context.annotation.Configuration
+
+/**
+ * Tests for {@link ConfigurationProperties @ConfigurationProperties}-annotated beans.
+ *
+ * @author Madhura Bhave
+ */
+class KotlinConfigurationPropertiesTests {
+
+	private var context = AnnotationConfigApplicationContext()
+
+	@Test //gh-18652
+	fun `type with constructor binding and existing singleton should not fail`() {
+		val beanFactory = this.context.beanFactory
+		(beanFactory as BeanDefinitionRegistry).registerBeanDefinition("foo",
+				RootBeanDefinition(BingProperties::class.java))
+		beanFactory.registerSingleton("foo", BingProperties(""))
+		this.context.register(TestConfig::class.java)
+		this.context.refresh();
+	}
+
+	@ConfigurationProperties(prefix = "foo")
+	@ConstructorBinding
+	class BingProperties(@Suppress("UNUSED_PARAMETER") bar: String) {
+
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@EnableConfigurationProperties
+	internal open class TestConfig {
+
+	}
+
+}
\ No newline at end of file