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 6bb5e7262..bec7213ba 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
@@ -125,6 +125,9 @@ public class BeanFactoryAwareFunctionRegistry
 	@Override
 	@SuppressWarnings("unchecked")
 	public <T> T lookup(String definition, String... acceptedOutputTypes) {
+		if (!StringUtils.hasText(definition)) {
+			definition = this.applicationContext.getEnvironment().getProperty("spring.cloud.function.definition");
+		}
 		Object function = this.proxyInvokerIfNecessary((FunctionInvocationWrapper) this.compose(null, definition, acceptedOutputTypes));
 		return (T) function;
 	}
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 431b5a6c4..8e897fff2 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
@@ -69,6 +69,27 @@ public class BeanFactoryAwareFunctionRegistryTests {
 		return catalog;
 	}
 
+	@Test
+	public void testDefaultLookup() throws Exception {
+		FunctionCatalog catalog = this.configureCatalog();
+		Object function = catalog.lookup("");
+		assertThat(function).isNull();
+		//==
+		System.setProperty("spring.cloud.function.definition", "uppercase");
+		function = catalog.lookup("");
+		assertThat(function).isNotNull();
+		Field field = ReflectionUtils.findField(FunctionInvocationWrapper.class, "composed");
+		field.setAccessible(true);
+		assertThat(((boolean) field.get(function))).isFalse();
+		//==
+		System.setProperty("spring.cloud.function.definition", "uppercase|uppercaseFlux");
+		function = catalog.lookup("");
+		assertThat(function).isNotNull();
+		field = ReflectionUtils.findField(FunctionInvocationWrapper.class, "composed");
+		field.setAccessible(true);
+		assertThat(((boolean) field.get(function))).isTrue();
+	}
+
 	@Test
 	public void testImperativeFunction() {
 		FunctionCatalog catalog = this.configureCatalog();
@@ -530,6 +551,7 @@ public class BeanFactoryAwareFunctionRegistryTests {
 		public void setId(int id) {
 			this.id = id;
 		}
+		@Override
 		public String toString() {
 			return "Person: " + name + "/" + id;
 		}
diff --git a/spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionDeployerTests.java b/spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionDeployerTests.java
index 6a0000a05..d73d04840 100644
--- a/spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionDeployerTests.java
+++ b/spring-cloud-function-deployer/src/test/java/org/springframework/cloud/function/deployer/FunctionDeployerTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2019 the original author or authors.
+ * Copyright 2017-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Function;
 
+import org.junit.Before;
 import org.junit.Test;
 import reactor.core.publisher.Flux;
 import reactor.util.function.Tuple2;
@@ -42,6 +43,11 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 public class FunctionDeployerTests {
 
+	@Before
+	public void before() {
+		System.clearProperty("spring.cloud.function.definition");
+	}
+
 	/*
 	 * Target function `class UpperCaseFunction implements Function<String, String>`
 	 * Main/Start class present, no Spring configuration