diff --git a/gallery_dl/extractor/deviantart.py b/gallery_dl/extractor/deviantart.py
index d73a8c7a..c5d410fc 100644
--- a/gallery_dl/extractor/deviantart.py
+++ b/gallery_dl/extractor/deviantart.py
@@ -126,8 +126,9 @@ class DeviantartExtractor(Extractor):
             if self.extra:
                 for match in DeviantartStashExtractor.pattern.finditer(
                         deviation.get("description", "")):
+                    url = text.ensure_http_scheme(match.group(0))
                     deviation["_extractor"] = DeviantartStashExtractor
-                    yield Message.Queue, match.group(0), deviation
+                    yield Message.Queue, url, deviation
 
     def deviations(self):
         """Return an iterable containing all relevant Deviation-objects"""
diff --git a/gallery_dl/extractor/newgrounds.py b/gallery_dl/extractor/newgrounds.py
index 17fe935e..84794ad9 100644
--- a/gallery_dl/extractor/newgrounds.py
+++ b/gallery_dl/extractor/newgrounds.py
@@ -224,10 +224,7 @@ class NewgroundsImageExtractor(NewgroundsExtractor):
             self.post_url = "https://www.newgrounds.com/art/view/{}/{}".format(
                 self.user, match.group(3))
         else:
-            url = match.group(0)
-            if not url.startswith("http"):
-                url = "https://" + url
-            self.post_url = url
+            self.post_url = text.ensure_http_scheme(match.group(0))
 
     def posts(self):
         return (self.post_url,)
@@ -414,6 +411,6 @@ class NewgroundsFollowingExtractor(NewgroundsFavoriteExtractor):
     @staticmethod
     def _extract_favorites(page):
         return [
-            "https://" + user.rpartition('"')[2].lstrip("/:")
+            text.ensure_http_scheme(user.rpartition('"')[2])
             for user in text.extract_iter(page, 'class="item-user', '"><img')
         ]
diff --git a/gallery_dl/extractor/patreon.py b/gallery_dl/extractor/patreon.py
index 570bd72c..a14ec9ca 100644
--- a/gallery_dl/extractor/patreon.py
+++ b/gallery_dl/extractor/patreon.py
@@ -98,8 +98,7 @@ class PatreonExtractor(Extractor):
         headers = {"Referer": self.root}
 
         while url:
-            if not url.startswith("http"):
-                url = "https://" + url.lstrip("/:")
+            url = text.ensure_http_scheme(url)
             posts = self.request(url, headers=headers).json()
 
             if "included" in posts:
diff --git a/gallery_dl/text.py b/gallery_dl/text.py
index 3bb63903..4dc0963a 100644
--- a/gallery_dl/text.py
+++ b/gallery_dl/text.py
@@ -60,6 +60,13 @@ def split_html(txt, sep=None):
         return []
 
 
+def ensure_http_scheme(url, scheme="https://"):
+    """Prepend 'scheme' to 'url' if it doesn't have one"""
+    if url and not url.startswith(("https://", "http://")):
+        return scheme + url.lstrip("/:")
+    return url
+
+
 def filename_from_url(url):
     """Extract the last part of an URL to use as a filename"""
     try:
diff --git a/test/test_text.py b/test/test_text.py
index 4f31d81c..aeb8096d 100644
--- a/test/test_text.py
+++ b/test/test_text.py
@@ -94,6 +94,33 @@ class TestText(unittest.TestCase):
         for value in INVALID:
             self.assertEqual(f(value), empty)
 
+    def test_ensure_http_scheme(self, f=text.ensure_http_scheme):
+        result = "https://example.org/filename.ext"
+
+        # standard usage
+        self.assertEqual(f(""), "")
+        self.assertEqual(f("example.org/filename.ext"), result)
+        self.assertEqual(f("/example.org/filename.ext"), result)
+        self.assertEqual(f("//example.org/filename.ext"), result)
+        self.assertEqual(f("://example.org/filename.ext"), result)
+
+        # no change
+        self.assertEqual(f(result), result)
+        self.assertEqual(
+            f("http://example.org/filename.ext"),
+            "http://example.org/filename.ext",
+        )
+
+        # ...
+        self.assertEqual(
+            f("htp://example.org/filename.ext"),
+            "https://htp://example.org/filename.ext",
+        )
+
+        # invalid arguments
+        for value in INVALID_ALT:
+            self.assertEqual(f(value), value)
+
     def test_filename_from_url(self, f=text.filename_from_url):
         result = "filename.ext"