diff --git a/youtube_dl/extractor/bdsmxtube.py b/youtube_dl/extractor/bdsmxtube.py
index 590e2f0a1..cebb57edd 100644
--- a/youtube_dl/extractor/bdsmxtube.py
+++ b/youtube_dl/extractor/bdsmxtube.py
@@ -21,7 +21,9 @@ class BdsmxTubeIE(VXXXIE):
             'duration': 68.0,
             'categories': ['Asian', 'Brunette', 'Cosplay', 'Fetish',
                            'Fuck Machine', 'Gagging', 'Japanese',
-                           'JAV Uncensored', 'Latex', 'Leather', 'POV']}
+                           'JAV Uncensored', 'Latex', 'Leather', 'POV'],
+            'age_limit': 18,
+        }
     }]
 
     def _download_info_object(self, video_id):
diff --git a/youtube_dl/extractor/blackporntube.py b/youtube_dl/extractor/blackporntube.py
index 0cdff8233..48780f310 100644
--- a/youtube_dl/extractor/blackporntube.py
+++ b/youtube_dl/extractor/blackporntube.py
@@ -21,7 +21,8 @@ class BlackPornTubeIE(VXXXIE):
             'duration': 193.0,
             'categories': ['BDSM', 'Bondage', 'Celebrity', 'Ebony', 'Fetish',
                            'Shibari Bondage', 'Solo Female',
-                           'Tattoo']
+                           'Tattoo'],
+            'age_limit': 18,
         }
     }]
 
diff --git a/youtube_dl/extractor/inporn.py b/youtube_dl/extractor/inporn.py
index 4bc5e052e..5b92d9ddb 100644
--- a/youtube_dl/extractor/inporn.py
+++ b/youtube_dl/extractor/inporn.py
@@ -20,7 +20,9 @@ class InPornIE(VXXXIE):
             'upload_date': '20220930',
             'duration': 480.0,
             'categories': ['Asian', 'Brunette', 'Casting', 'HD', 'Japanese',
-                           'JAV Uncensored']}
+                           'JAV Uncensored'],
+            'age_limit': 18,
+        },
     }]
 
     def _download_info_object(self, video_id):
diff --git a/youtube_dl/extractor/mrgay.py b/youtube_dl/extractor/mrgay.py
index 8d44463ab..badc4553e 100644
--- a/youtube_dl/extractor/mrgay.py
+++ b/youtube_dl/extractor/mrgay.py
@@ -21,6 +21,7 @@ class MrGayIE(VXXXIE):
             'duration': 834.0,
             'categories': ['Amateur', 'Asian', 'Brunette', 'Crossdressing',
                            'Japanese', 'Webcam'],
+            'age_limit': 18,
         }
     }]
 
diff --git a/youtube_dl/extractor/vxxx.py b/youtube_dl/extractor/vxxx.py
index bcde6555f..e53420a66 100644
--- a/youtube_dl/extractor/vxxx.py
+++ b/youtube_dl/extractor/vxxx.py
@@ -25,7 +25,9 @@ class VXXXIE(InfoExtractor):
             'duration': 2373.0,
             'categories': ['Anal', 'Asian', 'BDSM', 'Brunette', 'Toys',
                            'Fetish', 'HD', 'Interracial', 'MILF'],
-        }}]
+            'age_limit': 18,
+        }
+    }]
 
     def _download_info_object(self, video_id):
         return self._download_json(
@@ -83,6 +85,7 @@ class VXXXIE(InfoExtractor):
             'dislike_count': int(info_object['statistics']['dislikes']),
             'average_rating': float(info_object['statistics']['rating']),
             'categories': [category['title'] for category in info_object['categories'].values()],
+            'age_limit': 18,
             'formats': None
         }
 
diff --git a/youtube_dl/extractor/xmilf.py b/youtube_dl/extractor/xmilf.py
index a85788bb0..2ee849d14 100644
--- a/youtube_dl/extractor/xmilf.py
+++ b/youtube_dl/extractor/xmilf.py
@@ -21,6 +21,7 @@ class XMilfIE(VXXXIE):
             'duration': 480.0,
             'categories': ['Amateur', 'Big Tits', 'Brunette', 'Fetish', 'HD',
                            'Lingerie', 'MILF', 'Webcam'],
+            'age_limit': 18,
         }
     }]