diff --git a/src/main/java/org/elasticsearch/index/query/CustomScoreQueryParser.java b/src/main/java/org/elasticsearch/index/query/CustomScoreQueryParser.java
index c6195dbb764..f792efd6f4a 100644
--- a/src/main/java/org/elasticsearch/index/query/CustomScoreQueryParser.java
+++ b/src/main/java/org/elasticsearch/index/query/CustomScoreQueryParser.java
@@ -146,12 +146,12 @@ public class CustomScoreQueryParser implements QueryParser {
             if (script instanceof ExplainableSearchScript) {
                 script.setNextDocId(docId);
                 script.setNextScore(subQueryExpl.getValue());
-                exp = ((ExplainableSearchScript) script).explain();
+                exp = ((ExplainableSearchScript) script).explain(subQueryExpl);
             } else {
                 float score = score(docId, subQueryExpl.getValue());
-                exp = new Explanation(score, "script score function: product of:");
+                exp = new Explanation(score, "script score function: composed of:");
+                exp.addDetail(subQueryExpl);
             }
-            exp.addDetail(subQueryExpl);
             return exp;
         }
 
diff --git a/src/main/java/org/elasticsearch/script/ExplainableSearchScript.java b/src/main/java/org/elasticsearch/script/ExplainableSearchScript.java
index 60cf0b46f5a..8bb91724def 100644
--- a/src/main/java/org/elasticsearch/script/ExplainableSearchScript.java
+++ b/src/main/java/org/elasticsearch/script/ExplainableSearchScript.java
@@ -27,7 +27,9 @@ public interface ExplainableSearchScript extends SearchScript {
 
     /**
      * Build the explanation of the current document being scored
+     * 
+     * @param subQueryExpl the explanation of the subQuery 
      */
-    Explanation explain();
+    Explanation explain(Explanation subQueryExpl);
 
 }