diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelState.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelState.java
index b41deab1c4d91..3c352b4b7dec7 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelState.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/process/autodetect/state/ModelState.java
@@ -21,7 +21,7 @@ public final class ModelState {
      */
     public static final String TYPE = "model_state";
 
-    private static final Pattern V_5_4_DOC_ID_SUFFIX_REGEX = Pattern.compile("\\d{10}#\\d+");
+    private static final Pattern V_5_4_DOC_ID_SUFFIX_REGEX = Pattern.compile("^\\d{10}#\\d+$");
 
     public static String documentId(String jobId, String snapshotId, int docNum) {
         return jobId + "_" + TYPE + "_" + snapshotId + "#" + docNum;