diff --git a/api/src/main/java/io/cloudevents/v02/http/HTTPAttributeMapper.java b/api/src/main/java/io/cloudevents/v02/http/HTTPAttributeMapper.java
index a4d08a51..3e3e6586 100644
--- a/api/src/main/java/io/cloudevents/v02/http/HTTPAttributeMapper.java
+++ b/api/src/main/java/io/cloudevents/v02/http/HTTPAttributeMapper.java
@@ -33,7 +33,7 @@ import io.cloudevents.v02.ContextAttributes;
  */
 public class HTTPAttributeMapper {
 	
-	public static final String HEADER_PREFIX = "ce-";
+	static final String HEADER_PREFIX = "ce-";
 	
 	public static Map<String, String> map(final Map<String, Object> headers) {
 		Objects.requireNonNull(headers);