diff --git a/graylog-storage-opensearch2/src/main/java/org/graylog/storage/opensearch2/IndicesAdapterOS2.java b/graylog-storage-opensearch2/src/main/java/org/graylog/storage/opensearch2/IndicesAdapterOS2.java
index e2724148bd76..e7a6af831e3f 100644
--- a/graylog-storage-opensearch2/src/main/java/org/graylog/storage/opensearch2/IndicesAdapterOS2.java
+++ b/graylog-storage-opensearch2/src/main/java/org/graylog/storage/opensearch2/IndicesAdapterOS2.java
@@ -442,7 +442,7 @@ private List<List<String>> partition(final List<String> indices) {
         List<String> partition = new ArrayList<>();
         int length = 0;
         for(String index: indices) {
-            if(length > MAX_INDICES_URL_PART_LENGTH) {
+            if(length + index.length() > MAX_INDICES_URL_PART_LENGTH) {
                 partitions.add(partition);
                 partition = new ArrayList<>();
             }