diff --git a/gallery_dl/extractor/4chan.py b/gallery_dl/extractor/4chan.py
index bad34c7e..a74861c9 100644
--- a/gallery_dl/extractor/4chan.py
+++ b/gallery_dl/extractor/4chan.py
@@ -16,7 +16,7 @@ class FourchanThreadExtractor(chan.ChanThreadExtractor):
     pattern = [r"(?:https?://)?boards\.4chan\.org/([^/]+)/thread/(\d+)"]
     test = [("https://boards.4chan.org/tg/thread/15396072/", {
         "url": "39082ad166161966d7ba8e37f2173a824eb540f0",
-        "keyword": "38679a7c8054f535cba67cae13eef1ea7dbc8085",
+        "keyword": "7ae2f4049adf0d2f835eb91b6b26b7f4ec882e0a",
         "content": "3081ed85a5afaeb3f430f42540e7bb5eec1908cc",
     })]
     api_url = "https://a.4cdn.org/{board}/thread/{thread}.json"
diff --git a/gallery_dl/extractor/8chan.py b/gallery_dl/extractor/8chan.py
index 526c2905..f6b6904d 100644
--- a/gallery_dl/extractor/8chan.py
+++ b/gallery_dl/extractor/8chan.py
@@ -16,8 +16,8 @@ class InfinitychanThreadExtractor(chan.ChanThreadExtractor):
     pattern = [r"(?:https?://)?(?:www\.)?8ch\.net/([^/]+)/res/(\d+)"]
     test = [("https://8ch.net/tg/res/175887.html", {
         "url": "cb03fdc650ad8e796fdab553fbd5489f468d3f45",
-        "keyword": "c2a7f57422558dddaf3467b9a30018e847eb4fad",
-        "content": "9f51cdfee6942a18011996ca049baeb0a22f931b",
+        "keyword": "d313fa77f689ddcd45736f1e86bf63cf58614786",
+        "content": "81e21a3cc87f64f224a966f207e8e1731216c345",
     })]
     api_url = "https://8ch.net/{board}/res/{thread}.json"
     file_url = "https://8ch.net/{board}/src/{tim}{ext}"
diff --git a/gallery_dl/extractor/chan.py b/gallery_dl/extractor/chan.py
index 086f251d..8e0b1e77 100644
--- a/gallery_dl/extractor/chan.py
+++ b/gallery_dl/extractor/chan.py
@@ -36,13 +36,18 @@ class ChanThreadExtractor(Extractor):
         for post in posts:
             if "filename" not in post:
                 continue
-            post.update(self.metadata)
+            self.update(post)
             yield Message.Url, self.file_url.format_map(post), post
             if "extra_files" in post:
                 for file in post["extra_files"]:
-                    post.update(file)
+                    self.update(post, file)
                     yield Message.Url, self.file_url.format_map(post), post
 
+    def update(self, post, data=None):
+        """Update keyword dictionary"""
+        post.update(data or self.metadata)
+        post["extension"] = post["ext"][1:]
+
     @staticmethod
     def get_thread_title(post):
         """Return thread title from first post"""
diff --git a/gallery_dl/extractor/imgur.py b/gallery_dl/extractor/imgur.py
index e0a7e9af..930c4206 100644
--- a/gallery_dl/extractor/imgur.py
+++ b/gallery_dl/extractor/imgur.py
@@ -20,7 +20,7 @@ class ImgurAlbumExtractor(Extractor):
     pattern = [r"(?:https?://)?(?:www\.)?imgur\.com/(?:a|gallery)/([^/?&#]+)"]
     test = [("https://imgur.com/a/TcBmP", {
         "url": "ce3552f550a5b5316bd9c7ae02e21e39f30c0563",
-        "keyword": "8301572a22c139b5e0704ccaf2bcf49a111e2384",
+        "keyword": "21723f47bf4a42599d39fbf29c5f79323d420898",
     })]
 
     def __init__(self, match):
@@ -34,6 +34,7 @@ class ImgurAlbumExtractor(Extractor):
         yield Message.Directory, data
         for num, image in enumerate(imgs, 1):
             image["num"] = num
+            image["extension"] = image["ext"][1:]
             image.update(data)
             url = "https://i.imgur.com/" + image["hash"] + image["ext"]
             yield Message.Url, url, image