diff --git a/tests/__init__.py b/tests/__init__.py
index 1540b4305..bffe7a05f 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -17,6 +17,12 @@ import tempfile
 from pathlib import Path
 
 os.environ.setdefault("RETROBIOS_OFFLINE", "1")
+# The installer reads the XDG base directories as RetroArch and the
+# emulators do. The CI runner sets XDG_CONFIG_HOME to its own home, so tests
+# that fake HOME found the runner's folders instead of theirs. A test that
+# exercises one of them sets it for itself.
+for _name in ("XDG_CONFIG_HOME", "XDG_DATA_HOME", "XDG_CACHE_HOME"):
+    os.environ.pop(_name, None)
 # A test never waits on, nor blocks, the measurements running on the host.
 os.environ.setdefault(
     "RETROBIOS_PROBE_LOCK",