diff --git a/src/calibre/build_forms.py b/src/calibre/build_forms.py
index 39bf932873..d6e554fc17 100644
--- a/src/calibre/build_forms.py
+++ b/src/calibre/build_forms.py
@@ -43,9 +43,9 @@ def build_forms(srcdir, info=None, summary=False, check_for_migration=False):
     # Ensure that people running from source have all their forms rebuilt for
     # the qt5 migration
     force_compile = os.environ.get('CALIBRE_FORCE_BUILD_UI_FORMS', '') in ('1', 'yes', 'true')
-    if check_for_migration and not force_compile:
+    if check_for_migration:
         from calibre.gui2 import gprefs
-        force_compile = not gprefs.get(f'migrated_forms_to_qt{qt_major}', False)
+        force_compile |= not gprefs.get(f'migrated_forms_to_qt{qt_major}', False)
 
     for form in forms:
         compiled_form = form_to_compiled_form(form)
@@ -67,5 +67,5 @@ def build_forms(srcdir, info=None, summary=False, check_for_migration=False):
             num += 1
     if num:
         info('Compiled %d forms' % num)
-    if force_compile:
+    if check_for_migration and force_compile:
         gprefs.set(f'migrated_forms_to_qt{qt_major}', True)