diff --git a/lucene/core/src/java/org/apache/lucene/search/RegexpQuery.java b/lucene/core/src/java/org/apache/lucene/search/RegexpQuery.java
index 54d013529ab..152e6a65da1 100644
--- a/lucene/core/src/java/org/apache/lucene/search/RegexpQuery.java
+++ b/lucene/core/src/java/org/apache/lucene/search/RegexpQuery.java
@@ -97,7 +97,9 @@ public class RegexpQuery extends AutomatonQuery {
       buffer.append(term.field());
       buffer.append(":");
     }
+    buffer.append('/');
     buffer.append(term.text());
+    buffer.append('/');
     buffer.append(ToStringUtils.boost(getBoost()));
     return buffer.toString();
   }