diff --git a/ditto/core/templatetags/ditto_core.py b/ditto/core/templatetags/ditto_core.py
index 7e9b26c..cb18eae 100644
--- a/ditto/core/templatetags/ditto_core.py
+++ b/ditto/core/templatetags/ditto_core.py
@@ -160,8 +160,7 @@ def current_url_name(context):
     """
     url_name = False
     if context.request.resolver_match:
-        url_name = "{}:{}".format(
-            context.request.resolver_match.namespace,
-            context.request.resolver_match.url_name,
-        )
+        namespace = context.request.resolver_match.namespace
+        name = context.request.resolver_match.url_name
+        url_name = f"{namespace}:{name}"
     return url_name
diff --git a/ditto/core/views.py b/ditto/core/views.py
index 3b5de04..7dd6a03 100644
--- a/ditto/core/views.py
+++ b/ditto/core/views.py
@@ -240,8 +240,9 @@ def set_app_and_variety(self, **kwargs):
                     app_slug, variety_slug
                 )
             elif variety_slug:
-                msg = "'{}' is not a valid variety slug for the '{}' app slug.".format(
-                    variety_slug, app_slug
+                msg = (
+                    f"'{variety_slug}' is not a valid variety slug for "
+                    f"the '{app_slug}' app slug."
                 )
                 raise Http404(msg)
         elif app_slug:
diff --git a/ditto/flickr/admin.py b/ditto/flickr/admin.py
index d3d7152..12a3fc2 100644
--- a/ditto/flickr/admin.py
+++ b/ditto/flickr/admin.py
@@ -441,20 +441,18 @@ class PhotoAdmin(DittoItemModelAdmin):
 
     def show_thumb(self, instance):
         return mark_safe(
-            '<img src="{}" width="{}" height="{}" />'.format(
-                instance.thumbnail_url,
-                instance.thumbnail_width,
-                instance.thumbnail_height,
-            )
+            f'<img src="{instance.thumbnail_url}" '
+            f'width="{instance.thumbnail_width}" '
+            f'height="{instance.thumbnail_height}" />'
         )
 
     show_thumb.short_description = "Thumbnail"
 
     def show_image(self, instance):
         return mark_safe(
-            '<img src="{}" width="{}" height="{}" />'.format(
-                instance.small_url, instance.small_width, instance.small_height
-            )
+            f'<img src="{instance.small_url}" '
+            f'width="{instance.small_width}" '
+            f'height="{instance.small_height}" />'
         )
 
     show_image.short_description = "Small image"
diff --git a/ditto/flickr/fetch/fetchers.py b/ditto/flickr/fetch/fetchers.py
index 8078849..1c0e6e6 100644
--- a/ditto/flickr/fetch/fetchers.py
+++ b/ditto/flickr/fetch/fetchers.py
@@ -551,8 +551,9 @@ def _fetch_photos_in_photoset(self, photoset_id):
                     page=page_number,
                 )
             except FlickrError as err:
-                msg = "Error when fetching photos in photoset {} (page {}): {}".format(
-                    photoset_id, page_number, err
+                msg = (
+                    f"Error when fetching photos in photoset {photoset_id} "
+                    f"(page {page_number}): {err}"
                 )
                 raise FetchError(msg) from err
 
diff --git a/ditto/flickr/models.py b/ditto/flickr/models.py
index be95140..e403eb3 100644
--- a/ditto/flickr/models.py
+++ b/ditto/flickr/models.py
@@ -495,6 +495,9 @@ def upload_path(self, filename):
     class Meta:
         ordering = ("-post_time",)
 
+    def __str__(self):
+        return super().__str_(self)
+
     def save(self, *args, **kwargs):
         if self.taken_time:
             self.taken_year = self.taken_time.year
@@ -681,12 +684,9 @@ def _remote_image_url(self, size):
             # Medium size doesn't have a letter suffix.
             if self.PHOTO_SIZES[size]["suffix"]:
                 size_ext = "_{}".format(self.PHOTO_SIZES[size]["suffix"])
-            return "https://farm{}.static.flickr.com/{}/{}_{}{}.jpg".format(
-                self.farm,
-                self.server,
-                self.flickr_id,
-                self.secret,
-                size_ext,
+            return (
+                f"https://farm{self.farm}.static.flickr.com/{self.server}/"
+                f"{self.flickr_id}_{self.secret}{size_ext}.jpg"
             )
 
     def _video_url(self, size):
@@ -912,10 +912,9 @@ def avatar_url(self):
     def original_icon_url(self):
         """URL of the avatar/profile pic at Flickr."""
         if self.iconserver:
-            return "https://farm{}.staticflickr.com/{}/buddyicons/{}.jpg".format(
-                self.iconfarm,
-                self.iconserver,
-                self.nsid,
+            return (
+                f"https://farm{self.iconfarm}.staticflickr.com/{self.iconserver}"
+                f"/buddyicons/{self.nsid}.jpg"
             )
         else:
             return "https://www.flickr.com/images/buddyicon.gif"
diff --git a/ditto/flickr/templatetags/ditto_flickr.py b/ditto/flickr/templatetags/ditto_flickr.py
index 4fe8554..4007717 100644
--- a/ditto/flickr/templatetags/ditto_flickr.py
+++ b/ditto/flickr/templatetags/ditto_flickr.py
@@ -85,9 +85,8 @@ def photo_license(n):
     if n in licenses:
         if n in Photo.LICENSE_URLS and Photo.LICENSE_URLS[n] != "":
             return format_html(
-                '<a href="{}" title="More about permissions">{}</a>'.format(
-                    Photo.LICENSE_URLS[n], licenses[n]
-                )
+                f'<a href="{Photo.LICENSE_URLs[n]}" title="More about permissions">'
+                f"{licenses[n]}</a>"
             )
         else:
             return licenses[n]
diff --git a/ditto/lastfm/models.py b/ditto/lastfm/models.py
index cb8144e..c47e4d3 100644
--- a/ditto/lastfm/models.py
+++ b/ditto/lastfm/models.py
@@ -111,10 +111,8 @@ def get_absolute_url(self):
     @property
     def permalink(self):
         "The Album's URL at Last.fm."
-        return "{}/music/{}/{}".format(
-            LASTFM_URL_ROOT,
-            self.artist.original_slug,
-            self.original_slug,
+        return (
+            f"{LASTFM_URL_ROOT}/music/{self.artist.original_slug}/{self.original_slug}"
         )
 
     @property
@@ -339,10 +337,9 @@ def get_absolute_url(self):
     @property
     def permalink(self):
         "The Track's URL at Last.fm."
-        return "{}/music/{}/_/{}".format(
-            LASTFM_URL_ROOT,
-            self.artist.original_slug,
-            self.original_slug,
+        return (
+            f"{LASTFM_URL_ROOT}/music/{self.artist.original_slug}/_/"
+            f"{self.original_slug}"
         )
 
     @property
diff --git a/ditto/twitter/admin.py b/ditto/twitter/admin.py
index 089cb29..2ea2ef8 100644
--- a/ditto/twitter/admin.py
+++ b/ditto/twitter/admin.py
@@ -155,29 +155,24 @@ class MediaAdmin(admin.ModelAdmin):
 
     def show_thumb(self, instance):
         return mark_safe(
-            '<img src="{}" width="{}" height="{}" />'.format(
-                instance.thumbnail_url,
-                instance.thumbnail_w,
-                instance.thumbnail_h,
-            )
+            f'<img src="{instance.thumbnail_url}" width="{instance.thumbnail_w}" '
+            f'height="{instance.thumbnail_h}" />'
         )
 
     show_thumb.short_description = ""
 
     def show_image(self, instance):
         if instance.media_type == "photo":
-            html = '<img src="{}" width="{}" height="{}" />'.format(
-                instance.small_url,
-                instance.small_w,
-                instance.small_h,
+            html = (
+                f'<img src="{instance.small_url}" width="{instance.small_w}" '
+                f'height="{instance.small_h}" />'
             )
         else:
-            html = '<video width="{}" height="{}" poster="{}" controls preload="metadata"><source src="{}" type="{}"></video>'.format(  # noqa: E501
-                instance.small_w,
-                instance.small_h,
-                instance.small_url,
-                instance.video_url,
-                instance.video_mime_type,
+            html = (
+                f'<video width="{instance.small_w}" height="{instance.small_h}" '
+                f'poster="{instance.small_url}" controls preload="metadata">'
+                f'<source src="{instance.video_url}" type="{instance.video_mime_type}">'
+                "</video>"
             )
         return mark_safe(html)
 
diff --git a/ditto/twitter/models.py b/ditto/twitter/models.py
index 0153c9c..f173c71 100644
--- a/ditto/twitter/models.py
+++ b/ditto/twitter/models.py
@@ -607,9 +607,9 @@ def is_reply(self):
     def in_reply_to_url(self):
         "If it's a reply, the link to the tweet replied to."
         if self.is_reply:
-            return "https://twitter.com/{}/status/{}".format(
-                self.in_reply_to_screen_name,
-                self.in_reply_to_status_id,
+            return (
+                f"https://twitter.com/{self.in_reply_to_screen_name}/"
+                f"status/{self.in_reply_to_status_id}"
             )
         else:
             return ""
diff --git a/tests/pinboard/test_fetch.py b/tests/pinboard/test_fetch.py
index d8d4c55..8d2a491 100644
--- a/tests/pinboard/test_fetch.py
+++ b/tests/pinboard/test_fetch.py
@@ -74,10 +74,9 @@ def make_success_body(
         if method == "all":
             return posts_json
         else:
-            return '{{"date":"{}T09:48:31Z","user":"{}","posts":{}}}\t\n'.format(
-                post_date,
-                username,
-                posts_json,
+            return (
+                f'{{"date":"{post_date}T09:48:31Z","user":"{username}",'
+                f'"posts":{posts_json}}}\t\n'
             )
 
     # Check that all interface methods return expected results on success.
diff --git a/tests/twitter/test_fetch_fetchers.py b/tests/twitter/test_fetch_fetchers.py
index dd53f7f..dff5897 100644
--- a/tests/twitter/test_fetch_fetchers.py
+++ b/tests/twitter/test_fetch_fetchers.py
@@ -976,10 +976,9 @@ def test_saves_downloaded_image_file(self, download):
         FetchFiles()._fetch_and_save_file(self.image, "image")
         self.assertEqual(
             self.image.image_file.name,
-            "twitter/media/{}/{}/{}".format(
-                temp_filepath[-4:-2],
-                temp_filepath[-2:],
-                os.path.basename(temp_filepath),
+            (
+                f"twitter/media/{temp_filepath[-4:-2]}/{temp_filepath[-2:]}/"
+                f"{os.path.basename(temp_filepath)}",
             ),
         )
 
@@ -994,9 +993,8 @@ def test_saves_downloaded_mp4_file(self, download):
         FetchFiles()._fetch_and_save_file(self.animated_gif, "mp4")
         self.assertEqual(
             self.animated_gif.mp4_file.name,
-            "twitter/media/{}/{}/{}".format(
-                temp_filepath[-4:-2],
-                temp_filepath[-2:],
-                os.path.basename(temp_filepath),
+            (
+                f"twitter/media/{temp_filepath[-4:-2]}/{temp_filepath[-2:]}/"
+                f"{os.path.basename(temp_filepath)}",
             ),
         )