diff --git a/python/protocan/trends.py b/python/protocan/trends.py
index 22e2daa..e047e1b 100644
--- a/python/protocan/trends.py
+++ b/python/protocan/trends.py
@@ -129,7 +129,8 @@ def encode_settings(settings: Mapping[str, list[TrendSignal]]) -> str:
 def decode_settings(text: str) -> dict[str, list[TrendSignal]]:
     if len(text.encode("utf-8")) > MAX_FILE_BYTES:
         raise ValueError("Trend configuration exceeds 1 MiB")
-    root = json.loads(text.removeprefix("\ufeff"))
+    # Python 3.8 is used by the Windows 7 port; remove at most one BOM.
+    root = json.loads(text[1:] if text.startswith("\ufeff") else text)
     if not isinstance(root, dict) or root.get("format") != "setflash-trends" or type(root.get("version")) is not int or root["version"] != 1:
         raise ValueError("Unknown trend configuration format/version")
     profiles = root.get("profiles")
diff --git a/python/tests/test_plot.py b/python/tests/test_plot.py
index b229824..4470200 100644
--- a/python/tests/test_plot.py
+++ b/python/tests/test_plot.py
@@ -9,6 +9,7 @@ import unittest
 from protocan.plot import Bounds, Marker, Markers, PlotMath, Viewport
 
 
+@unittest.skipUnless(os.environ.get("SETPROTOCOL_LIBRARY"), "Set SETPROTOCOL_LIBRARY to the built C library")
 class PlotTests(unittest.TestCase):
     @classmethod
     def setUpClass(cls):