diff --git a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/RoutingFunction.java b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/RoutingFunction.java
index dd6b965b3..564836968 100644
--- a/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/RoutingFunction.java
+++ b/spring-cloud-function-context/src/main/java/org/springframework/cloud/function/context/config/RoutingFunction.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.function.context.config;
 
+import java.util.Map;
+import java.util.TreeMap;
 import java.util.function.Function;
 
 import org.apache.commons.logging.Log;
@@ -193,6 +195,10 @@ public class RoutingFunction implements Function<Object, Object> {
 
 	private FunctionInvocationWrapper functionFromExpression(String routingExpression, Object input) {
 		Expression expression = spelParser.parseExpression(routingExpression);
+		if (input instanceof Message) {
+			input = new MessageStructureWithCaseInsensitiveHeaderKeys((Message<?>) input);
+		}
+
 		String functionName = expression.getValue(this.evalContext, input, String.class);
 		Assert.hasText(functionName, "Failed to resolve function name based on routing expression '" + functionProperties.getRoutingExpression() + "'");
 		FunctionInvocationWrapper function = functionCatalog.lookup(functionName);
@@ -203,4 +209,24 @@ public class RoutingFunction implements Function<Object, Object> {
 		}
 		return function;
 	}
+
+	@SuppressWarnings({"rawtypes", "unused"})
+	private static class MessageStructureWithCaseInsensitiveHeaderKeys {
+		private final Object payload;
+		private final Map headers;
+
+		@SuppressWarnings("unchecked")
+		MessageStructureWithCaseInsensitiveHeaderKeys(Message message) {
+			this.payload = message.getPayload();
+			this.headers = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
+			this.headers.putAll(message.getHeaders());
+		}
+		public Object getPayload() {
+			return payload;
+		}
+
+		public Map getHeaders() {
+			return headers;
+		}
+	}
 }
diff --git a/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/config/RoutingFunctionTests.java b/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/config/RoutingFunctionTests.java
index cb9267b91..d3ef8210c 100644
--- a/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/config/RoutingFunctionTests.java
+++ b/spring-cloud-function-context/src/test/java/org/springframework/cloud/function/context/config/RoutingFunctionTests.java
@@ -134,6 +134,20 @@ public class RoutingFunctionTests {
 		assertThat(function.apply(message)).isEqualTo("olleh");
 	}
 
+	@SuppressWarnings({ "unchecked", "rawtypes" })
+	@Test
+	public void testInvocationWithMessageAndRoutingExpressionCaseInsensitive() {
+		System.setProperty(FunctionProperties.PREFIX + ".routing-expression", "headers.function_Name");
+		FunctionCatalog functionCatalog = this.configureCatalog();
+		Function function = functionCatalog.lookup(RoutingFunction.FUNCTION_NAME);
+		assertThat(function).isNotNull();
+		Message<String> message = MessageBuilder.withPayload("hello").setHeader("function_name", "reverse").build();
+		assertThat(function.apply(message)).isEqualTo("olleh");
+
+		System.setProperty(FunctionProperties.PREFIX + ".routing-expression", "headers.FunCtion_namE");
+		assertThat(function.apply(message)).isEqualTo("olleh");
+	}
+
 	@SuppressWarnings({ "rawtypes", "unchecked" })
 	@Test
 	public void testInvocationWithRoutingBeanExpression() {