diff --git a/form.php b/form.php
index a694f61..2178bc0 100644
--- a/form.php
+++ b/form.php
@@ -291,8 +291,6 @@ class formfield
       $res .= "  ";
     $res .= "</label>\n";
     $res .= "    <div class='col-sm-10'>\n";
-    if (is_string ($this->defaults))
-      $this->defaults = array ($this->defaults);
     if (count ($this->titles) === 0)
       $this->titles = array ("");
     foreach ($this->titles as $key=>$val)
@@ -316,13 +314,28 @@ class formfield
       $res .= "'";
       if (isset ($this->readonly) && $this->readonly !== FALSE)
         $res .= " disabled='disabled'";
-      if (count ($this->titles) === 1 && isset ($this->values) &&
-          $this->values !== "unset")
-        $res .= " checked='checked'";
-      elseif (isset ($this->values[$key]) && $this->values[$key] !== "unset")
-        $res .= " checked='checked'";
-      elseif (isset ($this->defaults[$key]) && $this->defaults[$key] !== "")
-        $res .= " checked='checked'";
+      // Do not check by default !
+      // Check is enable if not null, false, 'unset' or ''
+      if (count ($this->titles) === 1)
+      {
+        if (isset ($this->values) && $this->values !== "unset")
+          $res .= " checked='checked'";
+        elseif (count ($this->titles) === 1 && isset ($this->defaults) &&
+                $this->defaults !== null && $this->defaults !== false &&
+                $this->defaults !== "unset" && $this->defaults !== "")
+          $res .= " checked='checked'";
+      }
+      else
+      {
+        if (isset ($this->values[$key]) && $this->values[$key] !== "unset")
+          $res .= " checked='checked'";
+        elseif (isset ($this->defaults[$key]) && 
+                $this->defaults[$key] !== null && 
+                $this->defaults[$key] !== false &&
+                $this->defaults[$key] !== "unset" &&
+                $this->defaults[$key] !== "")
+          $res .= " checked='checked'";
+      }
       if (isset ($this->hidden) && $this->hidden !== FALSE)
         $res .= " style='display:none'";
       if (isset ($this->errors) || isset ($this->help))