diff --git a/changelog.d/3-bug-fixes/WPB-4425-fix-es-migration-script b/changelog.d/3-bug-fixes/WPB-4425-fix-es-migration-script
new file mode 100644
index 0000000000..66cbb38478
--- /dev/null
+++ b/changelog.d/3-bug-fixes/WPB-4425-fix-es-migration-script
@@ -0,0 +1 @@
+Fix ES migration script.
diff --git a/services/brig/src/Brig/Index/Migrations.hs b/services/brig/src/Brig/Index/Migrations.hs
index c6101df53a..27d7559fed 100644
--- a/services/brig/src/Brig/Index/Migrations.hs
+++ b/services/brig/src/Brig/Index/Migrations.hs
@@ -120,21 +120,21 @@ failIfIndexAbsent targetIndex =
 
 -- | Runs only the migrations which need to run
 runMigration :: MigrationVersion -> MigrationActionT IO ()
-runMigration ver = do
-  vmax <- latestMigrationVersion
-  if ver > vmax
+runMigration expectedVersion = do
+  foundVersion <- latestMigrationVersion
+  if expectedVersion > foundVersion
     then do
       Log.info $
         Log.msg (Log.val "Migration necessary.")
-          . Log.field "expectedVersion" vmax
-          . Log.field "foundVersion" ver
+          . Log.field "expectedVersion" expectedVersion
+          . Log.field "foundVersion" foundVersion
       Search.reindexAllIfSameOrNewer
-      persistVersion ver
+      persistVersion expectedVersion
     else do
       Log.info $
         Log.msg (Log.val "No migration necessary.")
-          . Log.field "expectedVersion" vmax
-          . Log.field "foundVersion" ver
+          . Log.field "expectedVersion" expectedVersion
+          . Log.field "foundVersion" foundVersion
 
 persistVersion :: (MonadThrow m, MonadIO m) => MigrationVersion -> MigrationActionT m ()
 persistVersion v =
@@ -148,6 +148,7 @@ persistVersion v =
                 . Log.field "migrationVersion" v
           else throwM $ PersistVersionFailed v $ show persistResponse
 
+-- | Which version is the table space currently running on?
 latestMigrationVersion :: (MonadThrow m, MonadIO m) => MigrationActionT m MigrationVersion
 latestMigrationVersion = do
   resp <- ES.parseEsResponse =<< ES.searchByIndex indexName (ES.mkSearch Nothing Nothing)