diff --git a/bridges/PinterestBridge.php b/bridges/PinterestBridge.php
index 8c24ecd..7f58e1d 100644
--- a/bridges/PinterestBridge.php
+++ b/bridges/PinterestBridge.php
@@ -16,7 +16,18 @@ class PinterestBridge extends BridgeAbstract{
     
     public function collectData(array $param){
         $html = '';
-        if (isset($param['u']) && isset($param['b'])) {
+        if (isset($param['u']) || isset($param['b'])) {
+        
+            if (empty($param['u']))
+            {
+                $this->returnError('You must specify a Pinterest username (?u=...).', 400);
+            }
+
+            if (empty($param['b']))
+            {
+                $this->returnError('You must specify a Pinterest board for this username (?b=...).', 400);
+            }
+            
             $this->username = $param['u'];
             $this->board = $param['b'];
             $html = file_get_html($this->getURI().'/'.urlencode($this->username).'/'.urlencode($this->board)) or $this->returnError('Could not request Pinterest.', 404);