diff --git a/gui/__init__.py b/gui/__init__.py
index 07fdf90..37b29db 100644
--- a/gui/__init__.py
+++ b/gui/__init__.py
@@ -19,9 +19,8 @@ self_dir = os.path.abspath(os.path.dirname(__file__))
 
 # Import anything that defines a command or parameter.
 import gui.commands
-import gui.params
-import gui.toplevel
 import gui.framecache
-
 # Hooks in to gdb.
 import gui.notify
+import gui.params
+import gui.toplevel
diff --git a/gui/adapt.py b/gui/adapt.py
index 9c0d5f6..606a94f 100644
--- a/gui/adapt.py
+++ b/gui/adapt.py
@@ -16,6 +16,7 @@
 # Adapt to gdb issues.
 
 import gdb
+
 import gui.params
 
 # The rule for adding a new entry here is that the bug must have some
diff --git a/gui/bpcache.py b/gui/bpcache.py
index dc33910..6518003 100644
--- a/gui/bpcache.py
+++ b/gui/bpcache.py
@@ -14,8 +14,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import gdb
-import gui.events
+
 import gui.adapt
+import gui.events
 
 # This maps from (FILENAME,LINE) to a set of breakpoints referencing
 # that file/line.  Then we emit events when entries are created or
diff --git a/gui/commands.py b/gui/commands.py
index 6715e8d..217ee87 100644
--- a/gui/commands.py
+++ b/gui/commands.py
@@ -13,18 +13,20 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
+
 import gdb
-import gui.startup
-import gui.source
-import gui.stack
-import gui.logwindow
-import gui.toplevel
+
+import gui.adapt
+import gui.display
 import gui.dprintf
 import gui.events
-import gui.display
 import gui.gdbutil
-import gui.adapt
-import re
+import gui.logwindow
+import gui.source
+import gui.stack
+import gui.startup
+import gui.toplevel
 from gui.startup import in_gtk_thread
 
 
diff --git a/gui/display.py b/gui/display.py
index b389fe2..8eff762 100644
--- a/gui/display.py
+++ b/gui/display.py
@@ -15,14 +15,16 @@
 
 # Log window.
 
-import gdb
-import gui.updatewindow
-import gui.startup
-from gi.repository import Gtk, Pango
 import functools
-from gui.startup import in_gdb_thread, in_gtk_thread
+from difflib import Differ, SequenceMatcher
+
+import gdb
+from gi.repository import Gtk, Pango
+
 import gui.events
-from difflib import SequenceMatcher, Differ
+import gui.startup
+import gui.updatewindow
+from gui.startup import in_gdb_thread, in_gtk_thread
 
 # FIXME: TO DO:
 # * highlight the changes
diff --git a/gui/dprintf.py b/gui/dprintf.py
index 9f01412..5cd7e89 100644
--- a/gui/dprintf.py
+++ b/gui/dprintf.py
@@ -16,6 +16,7 @@
 # dprintf-like machinery.
 
 import gdb
+
 import gui.logwindow
 from gui.startup import in_gdb_thread
 
diff --git a/gui/framecache.py b/gui/framecache.py
index 5f5ea57..f2ddb4f 100644
--- a/gui/framecache.py
+++ b/gui/framecache.py
@@ -14,10 +14,10 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import gdb
-import gui.events
-import gui.adapt
-import gui.invoker
 
+import gui.adapt
+import gui.events
+import gui.invoker
 from gui.startup import in_gdb_thread
 
 _last_selected_frame = None
diff --git a/gui/invoker.py b/gui/invoker.py
index a5ac051..f0a2738 100644
--- a/gui/invoker.py
+++ b/gui/invoker.py
@@ -14,6 +14,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import gdb
+
 from gui.startup import in_gdb_thread
 
 
diff --git a/gui/logwindow.py b/gui/logwindow.py
index 5e3c5c6..a8c6ec7 100644
--- a/gui/logwindow.py
+++ b/gui/logwindow.py
@@ -15,12 +15,13 @@
 
 # Log window.
 
-import gdb
-import gui.toplevel
-import gui.startup
 import functools
 
+import gdb
 from gi.repository import Gtk, Pango
+
+import gui.startup
+import gui.toplevel
 from gui.startup import in_gtk_thread
 
 default_log_window = None
diff --git a/gui/notify.py b/gui/notify.py
index 9e6e262..3c07070 100644
--- a/gui/notify.py
+++ b/gui/notify.py
@@ -15,13 +15,14 @@
 
 # Notifications
 
-import gdb
-import gui.params
-import gui.startup
 import time
 
+import gdb
 from gi.repository import Notify
-from gui.startup import in_gtk_thread, in_gdb_thread
+
+import gui.params
+import gui.startup
+from gui.startup import in_gdb_thread, in_gtk_thread
 
 _initialized = False
 
diff --git a/gui/params.py b/gui/params.py
index a9bdd79..4cf2352 100644
--- a/gui/params.py
+++ b/gui/params.py
@@ -17,12 +17,12 @@
 
 import gdb
 import gdb.prompt
+from gi.repository import GtkSource, Pango
+
 import gui.startup
 import gui.storage
 import gui.toplevel
-
 from gui.startup import in_gdb_thread, in_gtk_thread
-from gi.repository import GtkSource, Pango
 
 
 class _SetBase(gdb.Command):
diff --git a/gui/source.py b/gui/source.py
index a38a9ea..38e5bec 100644
--- a/gui/source.py
+++ b/gui/source.py
@@ -15,21 +15,22 @@
 
 # Source view.
 
-import gdb
-import gui
-import gui.updatewindow
-from gui.invoker import Invoker
-from gui.framecache import FrameCommandInvoker
-import gui.startup
-from gui.startup import in_gdb_thread, in_gtk_thread
-import gui.toplevel
-import gui.events
 import os.path
+
+import gdb
+from gi.repository import Gdk, GdkPixbuf, GObject, Gtk, GtkSource, Pango
+
+import gui
+import gui.bpcache
+import gui.events
 import gui.gdbutil
 import gui.params
-import gui.bpcache
-
-from gi.repository import Gtk, GtkSource, GObject, Gdk, GdkPixbuf, Pango
+import gui.startup
+import gui.toplevel
+import gui.updatewindow
+from gui.framecache import FrameCommandInvoker
+from gui.invoker import Invoker
+from gui.startup import in_gdb_thread, in_gtk_thread
 
 
 class BufferManager:
diff --git a/gui/stack.py b/gui/stack.py
index 9f2374d..9b23cba 100644
--- a/gui/stack.py
+++ b/gui/stack.py
@@ -16,16 +16,16 @@
 # Stack view.
 
 import gdb
-import gdb.frames
 import gdb.FrameDecorator
 import gdb.FrameIterator
-import gui.updatewindow
-import gui.startup
-import gui.params
+import gdb.frames
+from gi.repository import Gtk
 
+import gui.params
+import gui.startup
+import gui.updatewindow
 from gui.framecache import FrameCommandInvoker
 from gui.startup import in_gdb_thread, in_gtk_thread
-from gi.repository import Gtk
 
 
 def format_frame(frame):
diff --git a/gui/startup.py b/gui/startup.py
index 8812c86..cfb1d84 100644
--- a/gui/startup.py
+++ b/gui/startup.py
@@ -13,20 +13,21 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import gdb
-import threading
-import queue
 import os
 import os.path
-import gui
+import queue
+import threading
 
+import gdb
 import gi
 
+import gui
+
 gi.require_version("Gtk", "3.0")
 gi.require_version("GtkSource", "3.0")
 gi.require_version("Notify", "0.7")
 
-from gi.repository import Gtk, Gdk, GObject, GtkSource, GLib, GdkPixbuf
+from gi.repository import Gdk, GdkPixbuf, GLib, GObject, Gtk, GtkSource
 
 (read_pipe, write_pipe) = os.pipe()
 
diff --git a/gui/storage.py b/gui/storage.py
index 971057e..6397806 100644
--- a/gui/storage.py
+++ b/gui/storage.py
@@ -15,11 +15,12 @@
 
 # Storage management.
 
-from gi.repository import GLib
-import os
-import errno
-import configparser
 import atexit
+import configparser
+import errno
+import os
+
+from gi.repository import GLib
 
 
 class StorageManager:
diff --git a/gui/toplevel.py b/gui/toplevel.py
index d413632..2e3cd29 100644
--- a/gui/toplevel.py
+++ b/gui/toplevel.py
@@ -15,14 +15,15 @@
 
 # Toplevel handling.
 
+import threading
+
 import gdb
+from gi.repository import Pango
+
 import gui.gdbutil
 import gui.params
 import gui.startup
 import gui.storage
-import threading
-
-from gi.repository import Pango
 from gui.startup import in_gdb_thread, in_gtk_thread
 
 
diff --git a/gui/updatewindow.py b/gui/updatewindow.py
index 560e2e5..bfbc59d 100644
--- a/gui/updatewindow.py
+++ b/gui/updatewindow.py
@@ -15,11 +15,12 @@
 
 # Auto-updating window.
 
-from gui.toplevel import Toplevel
+import gdb
+
+import gui.events
 import gui.startup
 from gui.startup import in_gdb_thread, in_gtk_thread
-import gdb
-import gui.events
+from gui.toplevel import Toplevel
 
 
 class UpdateWindow(Toplevel):