diff --git a/modules/src/main/java/org/archive/modules/writer/WARCWriterProcessor.java b/modules/src/main/java/org/archive/modules/writer/WARCWriterProcessor.java
index e2b7e465..43e24ff3 100644
--- a/modules/src/main/java/org/archive/modules/writer/WARCWriterProcessor.java
+++ b/modules/src/main/java/org/archive/modules/writer/WARCWriterProcessor.java
@@ -708,7 +708,7 @@ public class WARCWriterProcessor extends WriterPoolProcessor implements WARCWrit
          * content."
          */
         headers.addLabelValue(HEADER_KEY_REFERS_TO, 
-                curi.getContentDigestHistory().get(A_WARC_RECORD_ID).toString());
+                "<" + curi.getContentDigestHistory().get(A_WARC_RECORD_ID) + ">");
         headers.addLabelValue(HEADER_KEY_REFERS_TO_TARGET_URI, 
                 curi.getContentDigestHistory().get(A_ORIGINAL_URL).toString());
         headers.addLabelValue(HEADER_KEY_REFERS_TO_DATE,