diff --git a/spring-integration-core/src/main/java/org/springframework/integration/config/IntegrationRegistrar.java b/spring-integration-core/src/main/java/org/springframework/integration/config/IntegrationRegistrar.java
index add0e542bb..9aaaf253f2 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/config/IntegrationRegistrar.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/config/IntegrationRegistrar.java
@@ -22,6 +22,7 @@ import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.ManagedSet;
+import org.springframework.context.ApplicationContextException;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.integration.aop.PublisherAnnotationBeanPostProcessor;
@@ -29,6 +30,7 @@ import org.springframework.integration.config.annotation.MessagingAnnotationPost
 import org.springframework.integration.context.IntegrationContextUtils;
 import org.springframework.integration.context.IntegrationProperties;
 import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
 
 /**
  * {@link ImportBeanDefinitionRegistrar} implementation that configures integration infrastructure.
@@ -40,6 +42,17 @@ import org.springframework.lang.Nullable;
  */
 public class IntegrationRegistrar implements ImportBeanDefinitionRegistrar {
 
+	static {
+		if (ClassUtils.isPresent("org.springframework.integration.dsl.support.Function",
+				IntegrationRegistrar.class.getClassLoader())) {
+
+			throw new ApplicationContextException("Starting with Spring Integration 5.0, "
+					+  "the 'spring-integration-java-dsl' dependency is no longer needed; "
+					+ "the Java DSL has been merged into the core project. "
+					+ "Having it present it on the classpath causes class loading conflicts.");
+		}
+	}
+
 	/**
 	 * Invoked by the framework when an @EnableIntegration annotation is encountered.
 	 * Also called with {@code null} {@code importingClassMetadata} from {@code AbstractIntegrationNamespaceHandler}