diff --git a/config.py b/config.py
index 167c6a5..8db88df 100644
--- a/config.py
+++ b/config.py
@@ -255,3 +255,18 @@ TRUSTED_DEFAULT_URLS = [
 # This MUST BE THE LAST!
 if os.path.isfile(os.path.join(BASE_DIR, "config_local.py")):
     from config_local import *  # noqa # flake8: noqa # NOQA # pragma: no cover
+
+def map_legacy_config(trusted_url):
+    """
+    For backward compability with the legacy configuration
+    for trusting URLs. Adapts them to fit the new config.
+    """
+    if isinstance(trusted_url, str):
+        return {
+            "url_prefix": trusted_url
+        }
+
+    return trusted_url
+
+# Backward compability for legacy behavior
+TRUSTED_DEFAULT_URLS = list(map(map_legacy_config, TRUSTED_DEFAULT_URLS))
diff --git a/ivatar/test_utils.py b/ivatar/test_utils.py
index 909a512..5ecf362 100644
--- a/ivatar/test_utils.py
+++ b/ivatar/test_utils.py
@@ -47,7 +47,7 @@ class Tester(TestCase):
         self.assertEqual(openid_variations(openid3)[3], openid3)
 
     def test_is_trusted_url(self):
-        test1 = is_trusted_url("https://gravatar.com/avatar/63a75a80e6b1f4adfdb04c1ca02e596c", [
+        test_gravatar_true = is_trusted_url("https://gravatar.com/avatar/63a75a80e6b1f4adfdb04c1ca02e596c", [
             {
                 "schemes": [
                     "http",
@@ -57,9 +57,9 @@ class Tester(TestCase):
                 "path_prefix": "/avatar/"
             }
         ])
-        self.assertTrue(test1)
+        self.assertTrue(test_gravatar_true)
 
-        test2 = is_trusted_url("https://gravatar.com.example.org/avatar/63a75a80e6b1f4adfdb04c1ca02e596c", [
+        test_gravatar_false = is_trusted_url("https://gravatar.com.example.org/avatar/63a75a80e6b1f4adfdb04c1ca02e596c", [
             {
                 "schemes": [
                     "http",
@@ -69,10 +69,9 @@ class Tester(TestCase):
                 "path_prefix": "/avatar/"
             }
         ])
-        self.assertFalse(test2)
+        self.assertFalse(test_gravatar_false)
 
-        # Test against open redirect with valid URL in query params
-        test3 = is_trusted_url("https://github.com/SethFalco/?boop=https://secure.gravatar.com/avatar/205e460b479e2e5b48aec07710c08d50", [
+        test_open_redirect = is_trusted_url("https://github.com/SethFalco/?boop=https://secure.gravatar.com/avatar/205e460b479e2e5b48aec07710c08d50", [
             {
                 "schemes": [
                     "http",
@@ -82,9 +81,9 @@ class Tester(TestCase):
                 "path_prefix": "/avatar/"
             }
         ])
-        self.assertFalse(test3)
+        self.assertFalse(test_open_redirect)
 
-        test4 = is_trusted_url("https://ui-avatars.com/api/blah", [
+        test_multiple_filters = is_trusted_url("https://ui-avatars.com/api/blah", [
             {
                 "schemes": [
                     "https"
@@ -101,4 +100,18 @@ class Tester(TestCase):
                 "path_prefix": "/avatar/"
             }
         ])
-        self.assertTrue(test4)
+        self.assertTrue(test_multiple_filters)
+
+        test_url_prefix_true = is_trusted_url("https://ui-avatars.com/api/blah", [
+            {
+                "url_prefix": "https://ui-avatars.com/api/"
+            }
+        ])
+        self.assertTrue(test_url_prefix_true)
+
+        test_url_prefix_false = is_trusted_url("https://ui-avatars.com/api/blah", [
+            {
+                "url_prefix": "https://gravatar.com/avatar/"
+            }
+        ])
+        self.assertFalse(test_url_prefix_false)
diff --git a/ivatar/utils.py b/ivatar/utils.py
index dc91b46..aea0920 100644
--- a/ivatar/utils.py
+++ b/ivatar/utils.py
@@ -149,6 +149,12 @@ def is_trusted_url(url, url_filters):
             if not path.startswith(path_prefix):
                 continue
 
+        if "url_prefix" in filter:
+            url_prefix = filter["url_prefix"]
+
+            if not url.startswith(url_prefix):
+                continue
+
         return True
 
     return False
diff --git a/ivatar/views.py b/ivatar/views.py
index e5e24cd..2569e61 100644
--- a/ivatar/views.py
+++ b/ivatar/views.py
@@ -141,18 +141,19 @@ class AvatarImageView(TemplateView):
         if "default" in request.GET:
             default = request.GET["default"]
 
-        # Check if default starts with an URL scheme and if it does,
-        # check if it's trusted
-        # Check for :// (schema)
-        if default is not None and default.find("://") > 0:
-            # Check if it's trusted, if not, reset to None
-            trusted_url = is_trusted_url(default, TRUSTED_DEFAULT_URLS)
-
-            if not trusted_url:
-                print(
-                    "Default URL is not in trusted URLs: '%s' ; Kicking it!" % default
-                )
+        if default is not None:
+            if TRUSTED_DEFAULT_URLS is None:
+                print("Query parameter `default` is disabled.")
                 default = None
+            elif default.find("://") > 0:
+                # Check if it's trusted, if not, reset to None
+                trusted_url = is_trusted_url(default, TRUSTED_DEFAULT_URLS)
+
+                if not trusted_url:
+                    print(
+                        "Default URL is not in trusted URLs: '%s' ; Kicking it!" % default
+                    )
+                    default = None
 
         if "f" in request.GET:
             if request.GET["f"] == "y":