diff --git a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistry.java b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistry.java
index dbfca43c4..4f6f284ae 100644
--- a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistry.java
+++ b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistry.java
@@ -16,13 +16,13 @@
 
 package org.springframework.cloud.function.context.catalog;
 
+import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -79,6 +79,7 @@ import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
 import org.springframework.util.MimeTypeUtils;
 import org.springframework.util.ObjectUtils;
+import org.springframework.util.ReflectionUtils;
 import org.springframework.util.StringUtils;
 
 
@@ -466,12 +467,16 @@ public class BeanFactoryAwareFunctionRegistry
 
 		private final String functionDefinition;
 
+		private final Field headersField;
+
 		FunctionInvocationWrapper(Object target, Type functionType, String functionDefinition, String... acceptedOutputMimeTypes) {
 			this.target = target;
 			this.composed = functionDefinition.contains("|") || target instanceof RoutingFunction;
 			this.functionType = functionType;
 			this.acceptedOutputMimeTypes = acceptedOutputMimeTypes;
 			this.functionDefinition = functionDefinition;
+			this.headersField = ReflectionUtils.findField(MessageHeaders.class, "headers");
+			this.headersField.setAccessible(true);
 		}
 
 		@Override
@@ -680,25 +685,24 @@ public class BeanFactoryAwareFunctionRegistry
 			return convertedValue;
 		}
 
-		@SuppressWarnings("rawtypes")
+		@SuppressWarnings({ "rawtypes", "unchecked" })
 		private Message convertValueToMessage(Object value,  Function<Message, Message> enricher, MimeType acceptedContentType) {
 			Message outputMessage = null;
-			if (enricher != null) {
-				if (!(value instanceof Message)) {
-					value = MessageBuilder.withPayload(value).setHeader(MessageHeaders.CONTENT_TYPE, acceptedContentType).build();
+			if (value instanceof Message) {
+				MessageHeaders headers = ((Message) value).getHeaders();
+				if (!headers.containsKey(MessageHeaders.CONTENT_TYPE)) {
+					Map<String, Object> headersMap = (Map<String, Object>) ReflectionUtils
+							.getField(this.headersField, headers);
+					headersMap.put(MessageHeaders.CONTENT_TYPE, acceptedContentType);
 				}
-				value = enricher.apply((Message) value);
-				outputMessage = messageConverter.toMessage(((Message) value).getPayload(), ((Message) value).getHeaders());
 			}
 			else {
-				if (value instanceof Message) {
-					outputMessage = messageConverter.toMessage(((Message) value).getPayload(), ((Message) value).getHeaders());
-				}
-				else {
-					outputMessage = messageConverter.toMessage(value,
-							new MessageHeaders(Collections.singletonMap(MessageHeaders.CONTENT_TYPE, acceptedContentType)));
-				}
+				value = MessageBuilder.withPayload(value).setHeader(MessageHeaders.CONTENT_TYPE, acceptedContentType).build();
 			}
+			if (enricher != null) {
+				value = enricher.apply((Message) value);
+			}
+			outputMessage = messageConverter.toMessage(((Message) value).getPayload(), ((Message) value).getHeaders());
 			return outputMessage;
 		}
 
diff --git a/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistryTests.java b/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistryTests.java
index 8e897fff2..10e471472 100644
--- a/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistryTests.java
+++ b/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/catalog/BeanFactoryAwareFunctionRegistryTests.java
@@ -83,7 +83,10 @@ public class BeanFactoryAwareFunctionRegistryTests {
 		assertThat(((boolean) field.get(function))).isFalse();
 		//==
 		System.setProperty("spring.cloud.function.definition", "uppercase|uppercaseFlux");
-		function = catalog.lookup("");
+		function = catalog.lookup("", "application/json");
+		Function<Flux<String>, Flux<Message<String>>> typedFunction = (Function<Flux<String>, Flux<Message<String>>>) function;
+		Object blockFirst = typedFunction.apply(Flux.just("hello")).blockFirst();
+		System.out.println(blockFirst);
 		assertThat(function).isNotNull();
 		field = ReflectionUtils.findField(FunctionInvocationWrapper.class, "composed");
 		field.setAccessible(true);