diff --git a/dblayeroo.php b/dblayeroo.php
index 8293140..72bc971 100644
--- a/dblayeroo.php
+++ b/dblayeroo.php
@@ -1892,7 +1892,7 @@ class dblayeroo
        "Invalid field to whereAdd '%s' : not defined in table", $field));
     $operator = strtoupper ($operator);
     $allowed = array ("=", "<=", ">=", "!=", "LIKE", "NOT LIKE", "IS NULL",
-                      "REGEXP", "NOT REGEXP");
+                      "IS NOT NULL", "REGEXP", "NOT REGEXP");
     if (! in_array ($operator, $allowed))
       $this->DBException ("Invalid operator provided (unknown operator)");
     // TODO : Check if the value is corresponding to the type of the column
@@ -1905,7 +1905,7 @@ class dblayeroo
       $operator = "~";
     if ($this->driver === "pgsql" && $operator === "NOT REGEXP")
       $operator = "!~";
-    if ($operator === "IS NULL")
+    if ($operator === "IS NULL" || $operator === "IS NOT NULL")
     {
       // Operator without parameter
       $this->whereExpression[] =