diff --git a/classes/core_userkey_manager.php b/classes/core_userkey_manager.php
index 8d66cd9..62b0714 100644
--- a/classes/core_userkey_manager.php
+++ b/classes/core_userkey_manager.php
@@ -93,7 +93,7 @@ class core_userkey_manager implements userkey_manager_interface {
             $this->iprestriction = getremoteaddr(null);
         }
 
-        if (isset($config->keylifetime) && is_int($config->keylifetime)) {
+        if (isset($config->keylifetime) && (int)$config->keylifetime > 0) {
             $this->validuntil = time() + $config->keylifetime;
         } else {
             $this->validuntil = time() + self::DEFAULT_KEY_LIFE_TIME_IN_SECONDS;
diff --git a/tests/core_userkey_manager_test.php b/tests/core_userkey_manager_test.php
index 3e62f22..6cc2c18 100644
--- a/tests/core_userkey_manager_test.php
+++ b/tests/core_userkey_manager_test.php
@@ -258,7 +258,7 @@ class core_userkey_manager_testcase extends advanced_testcase {
         $expectedscript = 'auth/userkey';
         $expectedinstance = $this->user->id;
         $expectediprestriction = null;
-        $expectedvaliduntil = time() + 60;
+        $expectedvaliduntil = time() + 3000;
 
         $this->assertEquals($expectedvalue, $actualkey->value);
         $this->assertEquals($expecteduserid, $actualkey->userid);