diff --git a/requirements.txt b/requirements.txt
index 0b8f9faa8a..3481dc8e00 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,6 +6,7 @@ PyJWT~=2.0
 pyobjc-core>=6.2, <10; sys_platform == 'darwin'
 pyobjc-framework-Cocoa>=6.2, <10; sys_platform == 'darwin'
 PyQt5-sip<=12.9.1; python_version < '3.7'
+PyQt5-sip<=12.15.0; python_version < '3.9'
 PyQt5~=5.11
 python-dateutil~=2.7
 pywin32; sys_platform == 'win32'