diff --git a/tools/psoc6/get-devs.py b/tools/psoc6/get-devs.py
index f556845eac8a..8ea99b6434a1 100644
--- a/tools/psoc6/get-devs.py
+++ b/tools/psoc6/get-devs.py
@@ -65,7 +65,7 @@ def get_kitprog_serial_number(udevadm_output_lines):
         for line in udevadm_output_lines:
             attr = re.search('ATTRS{serial}=="[a-zA-Z0-9]*"', str(line))
             if attr is not None:
-                sn = attr.group().removeprefix("ATTRS{serial}==")
+                sn = attr.group()[len("ATTRS{serial}==") :]
                 sn = sn.strip('"')
                 return sn