diff --git a/src/main/java/org/springframework/cloud/gateway/handler/predicate/HeaderRoutePredicate.java b/src/main/java/org/springframework/cloud/gateway/handler/predicate/HeaderRoutePredicate.java
index c87012fc..38c75820 100644
--- a/src/main/java/org/springframework/cloud/gateway/handler/predicate/HeaderRoutePredicate.java
+++ b/src/main/java/org/springframework/cloud/gateway/handler/predicate/HeaderRoutePredicate.java
@@ -3,7 +3,6 @@ package org.springframework.cloud.gateway.handler.predicate;
 import java.util.List;
 import java.util.function.Predicate;
 
-import org.springframework.util.Assert;
 import org.springframework.web.server.ServerWebExchange;
 
 /**
@@ -13,12 +12,12 @@ public class HeaderRoutePredicate implements RoutePredicate {
 
 	@Override
 	public Predicate<ServerWebExchange> apply(String header, String[] args) {
+		validate(args, 1);
+		String regexp = args[0];
+
 		//TODO: caching can happen here
 		return exchange -> {
-			Assert.isTrue(args != null && args.length == 1,
-					"args must have one entry");
 
-			String regexp = args[0];
 			List<String> values = exchange.getRequest().getHeaders().get(header);
 			for (String value : values) {
 				if (value.matches(regexp)) {
diff --git a/src/main/java/org/springframework/cloud/gateway/handler/predicate/RoutePredicate.java b/src/main/java/org/springframework/cloud/gateway/handler/predicate/RoutePredicate.java
index 0bdc223b..8a3e6765 100644
--- a/src/main/java/org/springframework/cloud/gateway/handler/predicate/RoutePredicate.java
+++ b/src/main/java/org/springframework/cloud/gateway/handler/predicate/RoutePredicate.java
@@ -2,6 +2,7 @@ package org.springframework.cloud.gateway.handler.predicate;
 
 import java.util.function.Predicate;
 
+import org.springframework.util.Assert;
 import org.springframework.web.server.ServerWebExchange;
 
 /**
@@ -10,4 +11,9 @@ import org.springframework.web.server.ServerWebExchange;
 public interface RoutePredicate {
 
 	Predicate<ServerWebExchange> apply(String value, String[] args);
+
+	default void validate(String[] args, int requiredSize) {
+		Assert.isTrue(args != null && args.length == requiredSize,
+				"args must have "+ requiredSize +" entry(s)");
+	}
 }