diff --git a/dblayer.php b/dblayer.php
index 1d59331..85eeaea 100644
--- a/dblayer.php
+++ b/dblayer.php
@@ -706,6 +706,8 @@ class dblayer
       // TODO Allow a field=>value in plus of array("field","value")
       foreach ($select as $n=>$s)
       {
+        if (! is_array ($s))
+          throw new Exception ("Select not an array for element $n", 500);
         // The foreign keys can not be in the select too (conflict)
         if (in_array ($s[0],$foreignSelectCols))
           continue;