diff --git a/gallery_dl/extractor/gelbooru_v02.py b/gallery_dl/extractor/gelbooru_v02.py
index 0864b9f6..0c8af3d5 100644
--- a/gallery_dl/extractor/gelbooru_v02.py
+++ b/gallery_dl/extractor/gelbooru_v02.py
@@ -168,7 +168,7 @@ INSTANCES = {
     },
     "rule34": {
         "root": "https://rule34.xxx",
-        "pattern": r"rule34\.xxx",
+        "pattern": r"(?:www\.)?rule34\.xxx",
         "api_root": "https://api.rule34.xxx",
     },
     "safebooru": {
diff --git a/test/results/rule34.py b/test/results/rule34.py
index ca90e511..f8fefa32 100644
--- a/test/results/rule34.py
+++ b/test/results/rule34.py
@@ -34,6 +34,13 @@ __tests__ = (
     "#count"   : 3,
 },
 
+{
+    "#url"     : "https://www.rule34.xxx/index.php?page=post&s=view&id=863",
+    "#comment" : "www subdomain",
+    "#category": ("gelbooru_v02", "rule34", "post"),
+    "#class"   : gelbooru_v02.GelbooruV02PostExtractor,
+},
+
 {
     "#url"     : "https://rule34.xxx/index.php?page=post&s=view&id=863",
     "#category": ("gelbooru_v02", "rule34", "post"),