diff --git a/weboob/backends/ina/backend.py b/weboob/backends/ina/backend.py
index 63c24c9b..436114ea 100644
--- a/weboob/backends/ina/backend.py
+++ b/weboob/backends/ina/backend.py
@@ -42,4 +42,4 @@ class InaBackend(BaseBackend, ICapVideo):
 
     def iter_search_results(self, pattern=None, sortby=ICapVideo.SEARCH_RELEVANCE, nsfw=False, required_fields=None):
         debug(u'backend ina: iter_search_results is not implemented')
-        return []
+        return
diff --git a/weboob/backends/youjizz/backend.py b/weboob/backends/youjizz/backend.py
index 7095adf0..81b5e929 100644
--- a/weboob/backends/youjizz/backend.py
+++ b/weboob/backends/youjizz/backend.py
@@ -44,6 +44,6 @@ class YoujizzBackend(BaseBackend, ICapVideo):
 
     def iter_search_results(self, pattern=None, sortby=ICapVideo.SEARCH_RELEVANCE, nsfw=False, required_fields=None):
         if not nsfw:
-            yield iter(set())
+            return
         for video in self.browser.iter_search_results(pattern, required_fields=required_fields):
             yield video
diff --git a/weboob/backends/youporn/backend.py b/weboob/backends/youporn/backend.py
index 5988e4bc..66660c08 100644
--- a/weboob/backends/youporn/backend.py
+++ b/weboob/backends/youporn/backend.py
@@ -41,7 +41,7 @@ class YoupornBackend(BaseBackend, ICapVideo):
     SORTBY = ['relevance', 'rating', 'views', 'time']
     def iter_search_results(self, pattern=None, sortby=ICapVideo.SEARCH_RELEVANCE, nsfw=False, required_fields=None):
         if not nsfw:
-            return iter(set())
+            return
         return self.browser.iter_search_results(pattern, self.SORTBY[sortby], required_fields=required_fields)
 
     def iter_page_urls(self, mozaic_url):