diff --git a/precheck/precheck.py b/precheck/precheck.py
index cc6f02e..366d3bc 100644
--- a/precheck/precheck.py
+++ b/precheck/precheck.py
@@ -7,10 +7,10 @@
 import traceback
 import xml.etree.ElementTree as ET
 
+import gdstk
 import klayout.db as pya
 import klayout.rdb as rdb
 from klayout_tools import parse_lyp_layers
-import gdstk
 
 PDK_ROOT = os.getenv("PDK_ROOT")
 PDK_NAME = os.getenv("PDK_NAME") or "sky130A"
@@ -28,7 +28,7 @@ class PrecheckFailure(Exception):
 
 def has_sky130_devices(gds: str):
     for cell_name in gdstk.read_rawcells(gds):
-        if cell_name.startswith('sky130_fd_'):
+        if cell_name.startswith("sky130_fd_"):
             return True
     return False