diff --git a/dblayer.php b/dblayer.php
index ddb5b34..6c27471 100644
--- a/dblayer.php
+++ b/dblayer.php
@@ -482,6 +482,10 @@ class dblayer extends PDO
     // Check if the foreign keys constrains are valid before doing the update
     foreach ($this->foreign as $foreign=>$data)
     {
+      // If the foreign keys are not modified, we don't check if they are
+      // correct
+      if (!isset ($datasOK[$foreign]))
+        continue;
       $table = $data[0];
       $column = $data[1];
       $req = "SELECT $column FROM `$this->tableprefix$table` ".