diff --git a/server/src/main/java/org/opensearch/cluster/routing/allocation/decider/RemoteStoreMigrationAllocationDecider.java b/server/src/main/java/org/opensearch/cluster/routing/allocation/decider/RemoteStoreMigrationAllocationDecider.java
index 518a3e98e64f4..3da6288292181 100644
--- a/server/src/main/java/org/opensearch/cluster/routing/allocation/decider/RemoteStoreMigrationAllocationDecider.java
+++ b/server/src/main/java/org/opensearch/cluster/routing/allocation/decider/RemoteStoreMigrationAllocationDecider.java
@@ -186,8 +186,8 @@ private String getDecisionDetails(
         String reason,
         RoutingAllocation allocation
     ) {
-        if (allocation.debugDecision()) {
-            return "";
+        if (allocation.debugDecision() == false) {
+            return null;
         }
         return new StringBuilder("[").append(migrationDirection.direction)
             .append(" migration_direction]: ")