diff --git a/setup/git_post_checkout_hook.py b/setup/git_post_checkout_hook.py
index f2e47cf582..c35ecd5e65 100755
--- a/setup/git_post_checkout_hook.py
+++ b/setup/git_post_checkout_hook.py
@@ -6,7 +6,32 @@ from __future__ import (unicode_literals, division, absolute_import,
 __license__ = 'GPL v3'
 __copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
 
-import os, subprocess
-base = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
-subprocess.check_call(['python', 'setup.py', 'gui'], cwd=base)
+import os, subprocess, sys
+
+prev_rev, current_rev, flags = [x.decode('utf-8') if isinstance(x, bytes) else x for x in sys.argv[1:]]
+def get_branch_name(rev):
+    return subprocess.check_output(['git', 'name-rev', '--name-only', rev]).decode('utf-8').strip()
+
+if flags == '1':  # A branch checkout
+
+    prev_branch, cur_branch = map(get_branch_name, (prev_rev, current_rev))
+    is_qt5_transition = 'qt5' in (prev_branch, cur_branch)
+
+    if is_qt5_transition:
+        # Remove compiled .ui files as they must be re-generated
+        for dirpath, dirnames, filenames in os.walk('.'):
+            for f in filenames:
+                if f.endswith('_ui.py'):
+                    os.remove(os.path.join(dirpath, f))
+
+    base = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+    os.chdir(base)
+    subprocess.check_call(['python', 'setup.py', 'gui'])
+
+    # Remove .pyc files as some of them might have been orphaned
+    for dirpath, dirnames, filenames in os.walk('.'):
+        for f in filenames:
+            if f.endswith('.pyc'):
+                os.remove(os.path.join(dirpath, f))
+