diff --git a/src/ORM/DataQuery.php b/src/ORM/DataQuery.php
index dd21d2bc2..2b4224be7 100644
--- a/src/ORM/DataQuery.php
+++ b/src/ORM/DataQuery.php
@@ -354,7 +354,6 @@ class DataQuery
     {
         if ($orderby = $query->getOrderBy()) {
             $newOrderby = array();
-            $i = 0;
             foreach ($orderby as $k => $dir) {
                 $newOrderby[$k] = $dir;
 
@@ -372,7 +371,6 @@ class DataQuery
                     if (isset($originalSelect[$col])) {
                         $query->selectField($originalSelect[$col], $col);
                     }
-
                     continue;
                 }
 
@@ -402,10 +400,15 @@ class DataQuery
                     if (!in_array($qualCol, $query->getSelect())) {
                         unset($newOrderby[$k]);
 
-                        $newOrderby["\"_SortColumn$i\""] = $dir;
-                        $query->selectField($qualCol, "_SortColumn$i");
+                        // Find the first free "_SortColumnX" slot
+                        // and assign it to $key
+                        $i = 0;
+                        while (isset($orderby[$key = "\"_SortColumn$i\""])) {
+                            ++$i;
+                        }
 
-                        $i++;
+                        $newOrderby[$key] = $dir;
+                        $query->selectField($qualCol, "_SortColumn$i");
                     }
                 }
             }
diff --git a/tests/php/ORM/DataQueryTest.php b/tests/php/ORM/DataQueryTest.php
index b9278a496..0c8a6bf41 100644
--- a/tests/php/ORM/DataQueryTest.php
+++ b/tests/php/ORM/DataQueryTest.php
@@ -296,6 +296,32 @@ class DataQueryTest extends SapphireTest
         static::resetDBSchema(true);
     }
 
+    public function testSurrogateFieldSort()
+    {
+        $query = new DataQuery(DataQueryTest\ObjectE::class);
+        $query->sort(
+            sprintf(
+                '(case when "Title" = %s then 1 else 0 end)',
+                DB::get_conn()->quoteString('Second')
+            ),
+            'DESC',
+            true
+        );
+        $query->sort('SortOrder', 'ASC', false);
+        $query->sort(
+            sprintf(
+                '(case when "Title" = %s then 0 else 1 end)',
+                DB::get_conn()->quoteString('Fourth')
+            ),
+            'DESC',
+            false
+        );
+        $this->assertEquals(
+            $query->execute()->column('Title'),
+            $query->column('Title')
+        );
+    }
+
     public function testComparisonClauseDateStartsWith()
     {
         DB::query("INSERT INTO \"DataQueryTest_F\" (\"MyDate\") VALUES ('1988-03-04 06:30')");