diff --git a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventsFunctionInvocationHelper.java b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventsFunctionInvocationHelper.java
index 25331f28a..9d1b6fa2b 100644
--- a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventsFunctionInvocationHelper.java
+++ b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/cloudevent/CloudEventsFunctionInvocationHelper.java
@@ -96,7 +96,15 @@ public class CloudEventsFunctionInvocationHelper implements FunctionInvocationHe
 		if (this.messageConverter != null && CLOUD_EVENT_CLASS != null && CLOUD_EVENT_CLASS.isAssignableFrom(result.getClass())) {
 			convertedResult = this.messageConverter.toMessage(result, input.getHeaders());
 		}
-		String targetPrefix = CloudEventMessageUtils.determinePrefixToUse(input.getHeaders(), true);
+
+		String targetPrefix = CloudEventMessageUtils.DEFAULT_ATTR_PREFIX;
+		if (input != null) {
+			targetPrefix = CloudEventMessageUtils.determinePrefixToUse(input.getHeaders(), true);
+		}
+		else if (result instanceof Message) {
+			targetPrefix = CloudEventMessageUtils.determinePrefixToUse(((Message<?>) result).getHeaders(), true);
+		}
+
 		Assert.hasText(targetPrefix, "Unable to determine prefix for Cloud Event atttributes, "
 				+ "which they must have according to protocol specification. Consider adding 'target-protocol' "
 				+ "header with values of one of the supported protocols - [kafka, amqp, http]");