diff --git a/datasette/cli.py b/datasette/cli.py
index 857320ed..51834c05 100644
--- a/datasette/cli.py
+++ b/datasette/cli.py
@@ -59,13 +59,18 @@ def publish(publisher, files, name, metadata, extra_options, force, branch, **ex
         """Exit (with error message) if ``binary` isn't installed"""
         if not shutil.which(binary):
             click.secho(
-                f" Publishing to {publish_target} requires {binary} to be installed and configured ",
+                "Publishing to {publish_target} requires {binary} to be installed and configured".format(
+                    publish_target=publish_target,
+                    binary=binary,
+                ),
                 bg='red',
                 fg='white',
                 bold=True,
                 err=True
             )
-            click.echo(f"Follow the instructions at {install_link}", err=True)
+            click.echo("Follow the instructions at {install_link}".format(
+                install_link=install_link,
+            ), err=True)
             sys.exit(1)
 
     if publisher == 'now':
@@ -87,10 +92,13 @@ def publish(publisher, files, name, metadata, extra_options, force, branch, **ex
             call(["heroku", "plugins:install", "heroku-builds"])
 
         with temporary_heroku_directory(files, name, metadata, extra_options, branch, extra_metadata):
-            create_output = check_output(['heroku', 'apps:create', '--json'])
+            create_output = check_output(
+                ['heroku', 'apps:create', '--json']
+            ).decode('utf8')
             app_name = json.loads(create_output)["name"]
             call(["heroku", "builds:create", "-a", app_name])
 
+
 @cli.command()
 @click.argument('files', type=click.Path(exists=True), nargs=-1, required=True)
 @click.option(
diff --git a/datasette/utils.py b/datasette/utils.py
index b5f323e4..c6ab18c8 100644
--- a/datasette/utils.py
+++ b/datasette/utils.py
@@ -151,8 +151,8 @@ def temporary_docker_directory(files, name, metadata, extra_options, branch=None
     os.mkdir(datasette_dir)
     saved_cwd = os.getcwd()
     file_paths = [
-        os.path.join(saved_cwd, name)
-        for name in files
+        os.path.join(saved_cwd, file_path)
+        for file_path in files
     ]
     file_names = [os.path.split(f)[-1] for f in files]
     if metadata:
@@ -185,8 +185,8 @@ def temporary_heroku_directory(files, name, metadata, extra_options, branch=None
     saved_cwd = os.getcwd()
 
     file_paths = [
-        os.path.join(saved_cwd, name)
-        for name in files
+        os.path.join(saved_cwd, file_path)
+        for file_path in files
     ]
     file_names = [os.path.split(f)[-1] for f in files]
 
@@ -207,7 +207,9 @@ def temporary_heroku_directory(files, name, metadata, extra_options, branch=None
         open('runtime.txt', 'w').write('python-3.6.2')
 
         if branch:
-            install_from = f'https://github.com/simonw/datasette/archive/{branch}.zip'
+            install_from = 'https://github.com/simonw/datasette/archive/{branch}.zip'.format(
+                branch=branch
+            )
         else:
             install_from = 'datasette'
 
@@ -216,7 +218,9 @@ def temporary_heroku_directory(files, name, metadata, extra_options, branch=None
         open('bin/post_compile', 'w').write('datasette build --inspect-file inspect-data.json')
 
         quoted_files = " ".join(map(shlex.quote, files))
-        procfile_cmd = f'web: datasette serve --host 0.0.0.0 {quoted_files} --cors --port $PORT --inspect-file inspect-data.json'
+        procfile_cmd = 'web: datasette serve --host 0.0.0.0 {quoted_files} --cors --port $PORT --inspect-file inspect-data.json'.format(
+            quoted_files=quoted_files,
+        )
         open('Procfile', 'w').write(procfile_cmd)
 
         for path, filename in zip(file_paths, file_names):