diff --git a/MD_STD_IN.php b/MD_STD_IN.php
index 4a648e5..c9f1ad3 100644
--- a/MD_STD_IN.php
+++ b/MD_STD_IN.php
@@ -145,10 +145,10 @@ final class MD_STD_IN {
      */
     final public static function sanitize_url($input):string {
 
-        if ($input === "") return $input;
+        if ($input === "") return "";
 
         $output = \filter_var($input, FILTER_SANITIZE_URL);
-        if (\filter_var($input, FILTER_VALIDATE_URL) === false) {
+        if (\filter_var($output, FILTER_VALIDATE_URL) === false) {
             throw new MDInvalidUrl("Invalid input URL");
         }
 
@@ -165,10 +165,10 @@ final class MD_STD_IN {
      */
     final public static function sanitize_email($input):string {
 
-        if ($input === "") return $input;
+        if ($input === "") return "";
 
         $output = \filter_var($input, FILTER_SANITIZE_EMAIL);
-        if (\filter_var($input, FILTER_VALIDATE_EMAIL) === false) {
+        if (\filter_var($output, FILTER_VALIDATE_EMAIL) === false) {
             throw new MDInvalidEmail("Invalid input email address");
         }