diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3a63d743..4555d3ca 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -7,14 +7,13 @@ workflows:
   version: 2
   test:
     jobs:
-      - test-3.5
       - test-3.6
       - test-3.7
 
 jobs:
-  test-3.5: &test-template
+  test-3.6: &test-template
     docker:
-      - image: circleci/python:3.5.6
+      - image: circleci/python:3.6.6
 
     working_directory: ~/repo
 
@@ -44,11 +43,6 @@ jobs:
           command: |
             xvfb-run -s "-screen 0 1280x1024x24" pytest --rungui --cov=onionshare --cov=onionshare_gui --cov-report=term-missing -vvv --no-qt-log tests/
 
-  test-3.6:
-    <<: *test-template
-    docker:
-      - image: circleci/python:3.6.6
-
   test-3.7:
     <<: *test-template
     docker:
diff --git a/onionshare/__init__.py b/onionshare/__init__.py
index 108ffd0b..a2d6d4a1 100644
--- a/onionshare/__init__.py
+++ b/onionshare/__init__.py
@@ -31,9 +31,9 @@ from .onionshare import OnionShare
 def build_url(common, app, web):
     # Build the URL
     if common.settings.get("public_mode"):
-        return "http://{0:s}".format(app.onion_host)
+        return f"http://{app.onion_host}"
     else:
-        return "http://onionshare:{0:s}@{1:s}".format(web.password, app.onion_host)
+        return f"http://onionshare:{web.password}@{app.onion_host}"
 
 
 def main(cwd=None):
@@ -44,7 +44,7 @@ def main(cwd=None):
     common = Common()
 
     # Display OnionShare banner
-    print("OnionShare {0:s} | https://onionshare.org/".format(common.version))
+    print(f"OnionShare {common.version} | https://onionshare.org/")
 
     # OnionShare CLI in OSX needs to change current working directory (#132)
     if common.platform == "Darwin":
@@ -160,10 +160,10 @@ def main(cwd=None):
         valid = True
         for filename in filenames:
             if not os.path.isfile(filename) and not os.path.isdir(filename):
-                print("{0:s} is not a valid file.".format(filename))
+                print(f"{filename} is not a valid file.")
                 valid = False
             if not os.access(filename, os.R_OK):
-                print("{0:s} is not a readable file.".format(filename))
+                print(f"{filename} is not a readable file.")
                 valid = False
         if not valid:
             sys.exit()
@@ -217,9 +217,7 @@ def main(cwd=None):
             schedule = datetime.now() + timedelta(seconds=autostart_timer)
             if mode == "receive":
                 print(
-                    "Files sent to you appear in this folder: {}".format(
-                        common.settings.get("data_dir")
-                    )
+                    f"Files sent to you appear in this folder: {common.settings.get('data_dir')}"
                 )
                 print("")
                 print(
@@ -228,30 +226,22 @@ def main(cwd=None):
                 print("")
                 if stealth:
                     print(
-                        "Give this address and HidServAuth lineto your sender, and tell them it won't be accessible until: {}".format(
-                            schedule.strftime("%I:%M:%S%p, %b %d, %y")
-                        )
+                        f"Give this address and HidServAuth lineto your sender, and tell them it won't be accessible until: {schedule.strftime('%I:%M:%S%p, %b %d, %y')}"
                     )
                     print(app.auth_string)
                 else:
                     print(
-                        "Give this address to your sender, and tell them it won't be accessible until: {}".format(
-                            schedule.strftime("%I:%M:%S%p, %b %d, %y")
-                        )
+                        f"Give this address to your sender, and tell them it won't be accessible until: {schedule.strftime('%I:%M:%S%p, %b %d, %y')}"
                     )
             else:
                 if stealth:
                     print(
-                        "Give this address and HidServAuth line to your recipient, and tell them it won't be accessible until: {}".format(
-                            schedule.strftime("%I:%M:%S%p, %b %d, %y")
-                        )
+                        f"Give this address and HidServAuth line to your recipient, and tell them it won't be accessible until: {schedule.strftime('%I:%M:%S%p, %b %d, %y')}"
                     )
                     print(app.auth_string)
                 else:
                     print(
-                        "Give this address to your recipient, and tell them it won't be accessible until: {}".format(
-                            schedule.strftime("%I:%M:%S%p, %b %d, %y")
-                        )
+                        f"Give this address to your recipient, and tell them it won't be accessible until: {schedule.strftime('%I:%M:%S%p, %b %d, %y')}"
                     )
             print(url)
             print("")
@@ -324,9 +314,7 @@ def main(cwd=None):
         else:
             if mode == "receive":
                 print(
-                    "Files sent to you appear in this folder: {}".format(
-                        common.settings.get("data_dir")
-                    )
+                    f"Files sent to you appear in this folder: {common.settings.get('data_dir')}"
                 )
                 print("")
                 print(
diff --git a/onionshare/common.py b/onionshare/common.py
index 3373462b..0a193d23 100644
--- a/onionshare/common.py
+++ b/onionshare/common.py
@@ -63,9 +63,9 @@ class Common(object):
         if self.verbose:
             timestamp = time.strftime("%b %d %Y %X")
 
-            final_msg = "[{}] {}.{}".format(timestamp, module, func)
+            final_msg = f"[{timestamp}] {module}.{func}"
             if msg:
-                final_msg = "{}: {}".format(final_msg, msg)
+                final_msg = f"{final_msg}: {msg}"
             print(final_msg)
 
     def get_resource_path(self, filename):
@@ -162,7 +162,7 @@ class Common(object):
         if self.platform == "Windows":
             try:
                 appdata = os.environ["APPDATA"]
-                onionshare_data_dir = "{}\\OnionShare".format(appdata)
+                onionshare_data_dir = f"{appdata}\\OnionShare"
             except:
                 # If for some reason we don't have the 'APPDATA' environment variable
                 # (like running tests in Linux while pretending to be in Windows)
@@ -437,7 +437,7 @@ class Common(object):
         """
         thresh = 1024.0
         if b < thresh:
-            return "{:.1f} B".format(b)
+            return f"{b} B"
         units = ("KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB")
         u = 0
         b /= thresh
@@ -517,7 +517,7 @@ class AutoStopTimer(threading.Thread):
 
     def run(self):
         self.common.log(
-            "AutoStopTimer", "Server will shut down after {} seconds".format(self.time)
+            "AutoStopTimer", f"Server will shut down after {self.time} seconds"
         )
         time.sleep(self.time)
         return 1
diff --git a/onionshare/onion.py b/onionshare/onion.py
index 727cf5f1..4e1491eb 100644
--- a/onionshare/onion.py
+++ b/onionshare/onion.py
@@ -219,9 +219,7 @@ class Onion(object):
                 dir=self.common.build_data_dir()
             )
             self.common.log(
-                "Onion",
-                "connect",
-                "tor_data_directory={}".format(self.tor_data_directory.name),
+                "Onion", "connect", f"tor_data_directory={self.tor_data_directory.name}"
             )
 
             # Create the torrc
@@ -283,9 +281,7 @@ class Onion(object):
                 # Bridge support
                 if self.settings.get("tor_bridges_use_obfs4"):
                     f.write(
-                        "ClientTransportPlugin obfs4 exec {}\n".format(
-                            self.obfs4proxy_file_path
-                        )
+                        f"ClientTransportPlugin obfs4 exec {self.obfs4proxy_file_path}\n"
                     )
                     with open(
                         self.common.get_resource_path("torrc_template-obfs4")
@@ -294,9 +290,7 @@ class Onion(object):
                             f.write(line)
                 elif self.settings.get("tor_bridges_use_meek_lite_azure"):
                     f.write(
-                        "ClientTransportPlugin meek_lite exec {}\n".format(
-                            self.obfs4proxy_file_path
-                        )
+                        f"ClientTransportPlugin meek_lite exec {self.obfs4proxy_file_path}\n"
                     )
                     with open(
                         self.common.get_resource_path("torrc_template-meek_lite_azure")
@@ -307,17 +301,13 @@ class Onion(object):
                 if self.settings.get("tor_bridges_use_custom_bridges"):
                     if "obfs4" in self.settings.get("tor_bridges_use_custom_bridges"):
                         f.write(
-                            "ClientTransportPlugin obfs4 exec {}\n".format(
-                                self.obfs4proxy_file_path
-                            )
+                            f"ClientTransportPlugin obfs4 exec {self.obfs4proxy_file_path}\n"
                         )
                     elif "meek_lite" in self.settings.get(
                         "tor_bridges_use_custom_bridges"
                     ):
                         f.write(
-                            "ClientTransportPlugin meek_lite exec {}\n".format(
-                                self.obfs4proxy_file_path
-                            )
+                            f"ClientTransportPlugin meek_lite exec {self.obfs4proxy_file_path}\n"
                         )
                     f.write(self.settings.get("tor_bridges_use_custom_bridges"))
                     f.write("\nUseBridges 1")
@@ -372,9 +362,7 @@ class Onion(object):
 
                 # "\033[K" clears the rest of the line
                 print(
-                    "Connecting to the Tor network: {}% - {}{}".format(
-                        progress, summary, "\033[K"
-                    ),
+                    f"Connecting to the Tor network: {progress}% - {summary}\033[K",
                     end="\r",
                 )
 
@@ -457,12 +445,12 @@ class Onion(object):
             if not found_tor:
                 try:
                     if self.common.platform == "Linux" or self.common.platform == "BSD":
-                        socket_file_path = "/run/user/{}/Tor/control.socket".format(
-                            os.geteuid()
+                        socket_file_path = (
+                            f"/run/user/{os.geteuid()}/Tor/control.socket"
                         )
                     elif self.common.platform == "Darwin":
-                        socket_file_path = "/run/user/{}/Tor/control.socket".format(
-                            os.geteuid()
+                        socket_file_path = (
+                            f"/run/user/{os.geteuid()}/Tor/control.socket"
                         )
                     elif self.common.platform == "Windows":
                         # Windows doesn't support unix sockets
@@ -542,7 +530,7 @@ class Onion(object):
         # Get the tor version
         self.tor_version = self.c.get_version().version_str
         self.common.log(
-            "Onion", "connect", "Connected to tor {}".format(self.tor_version)
+            "Onion", "connect", f"Connected to tor {self.tor_version}"
         )
 
         # Do the versions of stem and tor that I'm using support ephemeral onion services?
@@ -597,7 +585,7 @@ class Onion(object):
             raise TorTooOld(strings._("error_stealth_not_supported"))
 
         if not save_scheduled_key:
-            print("Setting up onion service on port {0:d}.".format(int(port)))
+            print(f"Setting up onion service on port {port}."
 
         if self.stealth:
             if self.settings.get("hidservauth_string"):
@@ -648,10 +636,10 @@ class Onion(object):
             basic_auth = None
             self.stealth = False
 
-        debug_message = "key_type={}".format(key_type)
+        debug_message = f"key_type={key_type}"
         if key_type == "NEW":
-            debug_message += ", key_content={}".format(key_content)
-        self.common.log("Onion", "start_onion_service", "{}".format(debug_message))
+            debug_message += f", key_content={key_content}"
+        self.common.log("Onion", "start_onion_service", debug_message)
         try:
             if basic_auth != None:
                 res = self.c.create_ephemeral_hidden_service(
@@ -700,25 +688,19 @@ class Onion(object):
                     self.auth_string = self.settings.get("hidservauth_string")
                 else:
                     auth_cookie = list(res.client_auth.values())[0]
-                    self.auth_string = "HidServAuth {} {}".format(
-                        onion_host, auth_cookie
-                    )
+                    self.auth_string = f"HidServAuth {onion_host} {auth_cookie}"
                     self.settings.set("hidservauth_string", self.auth_string)
             else:
                 if not self.scheduled_auth_cookie:
                     auth_cookie = list(res.client_auth.values())[0]
-                    self.auth_string = "HidServAuth {} {}".format(
-                        onion_host, auth_cookie
-                    )
+                    self.auth_string = f"HidServAuth {onion_host} {auth_cookie}"
                     if save_scheduled_key:
                         # Register the HidServAuth for the scheduled share
                         self.scheduled_auth_cookie = auth_cookie
                     else:
                         self.scheduled_auth_cookie = None
                 else:
-                    self.auth_string = "HidServAuth {} {}".format(
-                        onion_host, self.scheduled_auth_cookie
-                    )
+                    self.auth_string = f"HidServAuth {onion_host} {self.scheduled_auth_cookie}"
                     if not save_scheduled_key:
                         # We've used the scheduled share's HidServAuth. Reset it to None for future shares
                         self.scheduled_auth_cookie = None
@@ -741,14 +723,14 @@ class Onion(object):
             for onion in onions:
                 try:
                     self.common.log(
-                        "Onion", "cleanup", "trying to remove onion {}".format(onion)
+                        "Onion", "cleanup", f"trying to remove onion {onion}"
                     )
                     self.c.remove_ephemeral_hidden_service(onion)
                 except:
                     self.common.log(
                         "Onion",
                         "cleanup",
-                        "could not remove onion {}.. moving on anyway".format(onion),
+                        f"could not remove onion {onion}.. moving on anyway",
                     )
                     pass
         except:
diff --git a/onionshare/onionshare.py b/onionshare/onionshare.py
index 41a4e5a8..955f813d 100644
--- a/onionshare/onionshare.py
+++ b/onionshare/onionshare.py
@@ -56,7 +56,7 @@ class OnionShare(object):
         self.autostop_timer_thread = None
 
     def set_stealth(self, stealth):
-        self.common.log("OnionShare", "set_stealth", "stealth={}".format(stealth))
+        self.common.log("OnionShare", f"set_stealth", "stealth={stealth}")
 
         self.stealth = stealth
         self.onion.stealth = stealth
@@ -83,7 +83,7 @@ class OnionShare(object):
             self.autostop_timer_thread = AutoStopTimer(self.common, self.autostop_timer)
 
         if self.local_only:
-            self.onion_host = "127.0.0.1:{0:d}".format(self.port)
+            self.onion_host = f"127.0.0.1:{self.port}"
             return
 
         self.onion_host = self.onion.start_onion_service(
diff --git a/onionshare/settings.py b/onionshare/settings.py
index 25a28350..00854204 100644
--- a/onionshare/settings.py
+++ b/onionshare/settings.py
@@ -190,9 +190,7 @@ class Settings(object):
         # If the settings file exists, load it
         if os.path.exists(self.filename):
             try:
-                self.common.log(
-                    "Settings", "load", "Trying to load {}".format(self.filename)
-                )
+                self.common.log("Settings", "load", f"Trying to load {self.filename}")
                 with open(self.filename, "r") as f:
                     self._settings = json.load(f)
                     self.fill_in_defaults()
@@ -211,9 +209,7 @@ class Settings(object):
         """
         self.common.log("Settings", "save")
         open(self.filename, "w").write(json.dumps(self._settings, indent=2))
-        self.common.log(
-            "Settings", "save", "Settings saved in {}".format(self.filename)
-        )
+        self.common.log("Settings", "save", f"Settings saved in {self.filename}")
 
     def get(self, key):
         return self._settings[key]
diff --git a/onionshare/strings.py b/onionshare/strings.py
index 76360a42..0ea2ba24 100644
--- a/onionshare/strings.py
+++ b/onionshare/strings.py
@@ -36,7 +36,7 @@ def load_strings(common):
     translations = {}
     for locale in common.settings.available_locales:
         locale_dir = common.get_resource_path("locale")
-        filename = os.path.join(locale_dir, "{}.json".format(locale))
+        filename = os.path.join(locale_dir, f"{locale}.json")
         with open(filename, encoding="utf-8") as f:
             translations[locale] = json.load(f)
 
diff --git a/onionshare/web/receive_mode.py b/onionshare/web/receive_mode.py
index 90f000b9..c69a821d 100644
--- a/onionshare/web/receive_mode.py
+++ b/onionshare/web/receive_mode.py
@@ -38,7 +38,7 @@ class ReceiveModeWeb:
             self.cur_history_id += 1
             self.web.add_request(
                 self.web.REQUEST_INDIVIDUAL_FILE_STARTED,
-                "{}".format(request.path),
+                request.path,
                 {"id": history_id, "status_code": 200},
             )
 
@@ -79,11 +79,9 @@ class ReceiveModeWeb:
                     self.common.log(
                         "ReceiveModeWeb",
                         "define_routes",
-                        "/upload, uploaded {}, saving to {}".format(
-                            f.filename, local_path
-                        ),
+                        f"/upload, uploaded {f.filename}, saving to {local_path}",
                     )
-                    print("\n" + "Received: {}".format(local_path))
+                    print(f"\nReceived: {local_path}")
 
             if request.upload_error:
                 self.common.log(
@@ -98,9 +96,7 @@ class ReceiveModeWeb:
                     {"receive_mode_dir": request.receive_mode_dir},
                 )
                 print(
-                    "Could not create OnionShare data folder: {}".format(
-                        request.receive_mode_dir
-                    )
+                    f"Could not create OnionShare data folder: {request.receive_mode_dir}"
                 )
 
                 msg = "Error uploading, please inform the OnionShare user"
@@ -124,7 +120,7 @@ class ReceiveModeWeb:
             else:
                 msg = "Sent "
                 for filename in filenames:
-                    msg += "{}, ".format(filename)
+                    msg += f"{filename}, "
                 msg = msg.rstrip(", ")
                 if ajax:
                     info_flashes.append(msg)
@@ -191,7 +187,7 @@ class ReceiveModeFile(object):
         self.onionshare_close_func = close_func
 
         self.filename = os.path.join(self.onionshare_request.receive_mode_dir, filename)
-        self.filename_in_progress = "{}.part".format(self.filename)
+        self.filename_in_progress = f"{self.filename}.part"
 
         # Open the file
         self.upload_error = False
@@ -309,7 +305,7 @@ class ReceiveModeRequest(Request):
                     # Keep going until we find a directory name that's available
                     i = 1
                     while True:
-                        new_receive_mode_dir = "{}-{}".format(self.receive_mode_dir, i)
+                        new_receive_mode_dir = f"{self.receive_mode_dir}-{i}"
                         try:
                             os.makedirs(new_receive_mode_dir, 0o700, exist_ok=False)
                             self.receive_mode_dir = new_receive_mode_dir
@@ -333,9 +329,7 @@ class ReceiveModeRequest(Request):
                     {"receive_mode_dir": self.receive_mode_dir},
                 )
                 print(
-                    "Could not create OnionShare data folder: {}".format(
-                        self.receive_mode_dir
-                    )
+                    f"Could not create OnionShare data folder: {self.receive_mode_dir}"
                 )
                 self.web.common.log(
                     "ReceiveModeRequest",
@@ -460,12 +454,7 @@ class ReceiveModeRequest(Request):
                 self.previous_file = filename
 
             print(
-                "\r=> {:15s} {}".format(
-                    self.web.common.human_readable_filesize(
-                        self.progress[filename]["uploaded_bytes"]
-                    ),
-                    filename,
-                ),
+                f"\r=> {self.web.common.human_readable_filesize(self.progress[filename]['uploaded_bytes'])} {filename}",
                 end="",
             )
 
diff --git a/onionshare/web/send_base_mode.py b/onionshare/web/send_base_mode.py
index fe7e57f8..c2086f15 100644
--- a/onionshare/web/send_base_mode.py
+++ b/onionshare/web/send_base_mode.py
@@ -95,16 +95,14 @@ class SendBaseModeWeb:
         self.cur_history_id += 1
         self.web.add_request(
             self.web.REQUEST_INDIVIDUAL_FILE_STARTED,
-            "/{}".format(path),
+            f"/{path}",
             {"id": history_id, "method": request.method, "status_code": 200},
         )
 
         breadcrumbs = [("☗", "/")]
         parts = path.split("/")[:-1]
         for i in range(len(parts)):
-            breadcrumbs.append(
-                ("{}".format(parts[i]), "/{}/".format("/".join(parts[0 : i + 1])))
-            )
+            breadcrumbs.append((parts[i], f"/{'/'.join(parts[0 : i + 1])}/"))
         breadcrumbs_leaf = breadcrumbs.pop()[0]
 
         # If filesystem_path is None, this is the root directory listing
@@ -173,7 +171,6 @@ class SendBaseModeWeb:
             {"id": history_id, "filesize": filesize},
         )
 
-
         def generate():
             chunk_size = 102400  # 100kb
 
diff --git a/onionshare/web/share_mode.py b/onionshare/web/share_mode.py
index 21dea639..da20c328 100644
--- a/onionshare/web/share_mode.py
+++ b/onionshare/web/share_mode.py
@@ -340,8 +340,8 @@ class ZipWriter(object):
         if zip_filename:
             self.zip_filename = zip_filename
         else:
-            self.zip_filename = "{0:s}/onionshare_{1:s}.zip".format(
-                tempfile.mkdtemp(), self.common.random_string(4, 6)
+            self.zip_filename = (
+                f"{tempfile.mkdtemp()}/onionshare_{self.common.random_string(4, 6)}.zip"
             )
 
         self.z = zipfile.ZipFile(self.zip_filename, "w", allowZip64=True)
diff --git a/onionshare/web/web.py b/onionshare/web/web.py
index de2d71b5..d630060d 100644
--- a/onionshare/web/web.py
+++ b/onionshare/web/web.py
@@ -62,15 +62,13 @@ class Web:
 
     def __init__(self, common, is_gui, mode="share"):
         self.common = common
-        self.common.log("Web", "__init__", "is_gui={}, mode={}".format(is_gui, mode))
+        self.common.log("Web", "__init__", f"is_gui={is_gui}, mode={mode}")
 
         # The flask app
         self.app = Flask(
             __name__,
             static_folder=self.common.get_resource_path("static"),
-            static_url_path="/static_".format(
-                self.common.random_string(16)
-            ),  # randomize static_url_path to avoid making /static unusable
+            static_url_path=f"/static_{self.common.random_string(16)}",  # randomize static_url_path to avoid making /static unusable
             template_folder=self.common.get_resource_path("templates"),
         )
         self.app.secret_key = self.common.random_string(8)
@@ -154,11 +152,11 @@ class Web:
     def generate_static_url_path(self):
         # The static URL path has a 128-bit random number in it to avoid having name
         # collisions with files that might be getting shared
-        self.static_url_path = "/static_{}".format(self.common.random_string(16))
+        self.static_url_path = f"/static_{self.common.random_string(16)}"
         self.common.log(
             "Web",
             "generate_static_url_path",
-            "new static_url_path is {}".format(self.static_url_path),
+            f"new static_url_path is {self.static_url_path}",
         )
 
         # Update the flask route to handle the new static URL path
@@ -218,7 +216,7 @@ class Web:
             @self.app.route("/favicon.ico")
             def favicon():
                 return send_file(
-                    "{}/img/favicon.ico".format(self.common.get_resource_path("static"))
+                    f"{self.common.get_resource_path("static")}/img/favicon.ico"
                 )
 
     def error401(self):
@@ -228,7 +226,7 @@ class Web:
                 auth["username"] == "onionshare"
                 and auth["password"] not in self.invalid_passwords
             ):
-                print("Invalid password guess: {}".format(auth["password"]))
+                print(f"Invalid password guess: {auth["password"]}"
                 self.add_request(Web.REQUEST_INVALID_PASSWORD, data=auth["password"])
 
                 self.invalid_passwords.append(auth["password"])
@@ -256,7 +254,7 @@ class Web:
     def error404(self, history_id):
         self.add_request(
             self.REQUEST_INDIVIDUAL_FILE_STARTED,
-            "{}".format(request.path),
+            request.path,
             {"id": history_id, "status_code": 404},
         )
 
@@ -269,7 +267,7 @@ class Web:
     def error405(self, history_id):
         self.add_request(
             self.REQUEST_INDIVIDUAL_FILE_STARTED,
-            "{}".format(request.path),
+            request.path,
             {"id": history_id, "status_code": 405},
         )
 
@@ -311,21 +309,21 @@ class Web:
         self.common.log(
             "Web",
             "generate_password",
-            "persistent_password={}".format(persistent_password),
+            f"persistent_password={persistent_password}",
         )
         if persistent_password != None and persistent_password != "":
             self.password = persistent_password
             self.common.log(
                 "Web",
                 "generate_password",
-                'persistent_password sent, so password is: "{}"'.format(self.password),
+                f'persistent_password sent, so password is: "{self.password}"',
             )
         else:
             self.password = self.common.build_password()
             self.common.log(
                 "Web",
                 "generate_password",
-                'built random password: "{}"'.format(self.password),
+                f'built random password: "{self.password}"',
             )
 
     def verbose_mode(self):
@@ -362,9 +360,7 @@ class Web:
         self.common.log(
             "Web",
             "start",
-            "port={}, stay_open={}, public_mode={}, password={}".format(
-                port, stay_open, public_mode, password
-            ),
+            f"port={port}, stay_open={stay_open}, public_mode={public_mode}, password={password}",
         )
 
         self.stay_open = stay_open
@@ -398,7 +394,7 @@ class Web:
         # (We're putting the shutdown_password in the path as well to make routing simpler)
         if self.running:
             requests.get(
-                "http://127.0.0.1:{}/{}/shutdown".format(port, self.shutdown_password),
+                f"http://127.0.0.1:{port}/{self.shutdown_password}/shutdown",
                 auth=requests.auth.HTTPBasicAuth("onionshare", self.password),
             )
 
diff --git a/stdeb.cfg b/stdeb.cfg
index 0a200132..51ff9a0c 100644
--- a/stdeb.cfg
+++ b/stdeb.cfg
@@ -3,4 +3,4 @@ Package3: onionshare
 Depends3: python3, python3-flask, python3-flask-httpauth, python3-stem, python3-pyqt5, python3-crypto, python3-socks, python3-distutils, python-nautilus, tor, obfs4proxy
 Build-Depends: python3, python3-all, python3-pytest, python3-requests, python3-flask, python3-flask-httpauth, python3-stem, python3-pyqt5, python3-crypto, python3-socks, python3-distutils
 Suite: disco
-X-Python3-Version: >= 3.5.3
+X-Python3-Version: >= 3.6