diff --git a/SConstruct b/SConstruct
index 23ab37dc1e..74680c0598 100644
--- a/SConstruct
+++ b/SConstruct
@@ -327,6 +327,7 @@ qt_flags = [
 qt_env['CXXFLAGS'] += qt_flags
 qt_env['LIBPATH'] += ['#selfdrive/ui']
 qt_env['LIBS'] = qt_libs
+qt_env['QT_MOCHPREFIX'] = cache_dir + '/moc_files/moc_'
 
 if GetOption("clazy"):
   checks = [