diff --git a/requirements.txt b/requirements.txt
index 5a192ca5a2b91b7e207b3bcd85d9b50e50d3e3ba..f2e199a70d0df4a8b9a3695204411baac2cf4b2a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -34,7 +34,7 @@ pyserial==3.4
 python-dateutil==2.7.3
 python-ldap==3.4.0 ; sys_platform != 'win32'  # min version = 3.2.0 (Focal with security backports)
 python-stdnum==1.13
-pytz==2019.3
+pytz  # no version pinning to avoid OS perturbations
 pyusb==1.0.2
 qrcode==6.1
 reportlab==3.5.59 # version < 3.5.54 are not compatible with Pillow 8.1.2 and 3.5.59 is bullseye