diff --git a/api/schema.py b/api/schema.py
index fdfdd2b..42f328f 100644
--- a/api/schema.py
+++ b/api/schema.py
@@ -46,18 +46,27 @@ def _default_command() -> str:
     """Return the default shell command to run wecker.py from crontab."""
     project_root = _project_root()
     python_exec = sys.executable
-    return f"cd {project_root} && {python_exec} wecker.py >> wecker.log 2>&1"
+    runtime_dir = f"/run/user/{os.getuid()}"
+    return (
+        f"cd {project_root} && "
+        f"XDG_RUNTIME_DIR={runtime_dir} SDL_AUDIODRIVER=pulse "
+        f"{python_exec} wecker.py >> wecker.log 2>&1"
+    )
 
 
 def _start_wecker_process() -> subprocess.Popen:
     """Start wecker.py without invoking a shell."""
     project_root = _project_root()
+    env = os.environ.copy()
+    env.setdefault("SDL_AUDIODRIVER", "pulse")
+    env.setdefault("XDG_RUNTIME_DIR", f"/run/user/{os.getuid()}")
     return subprocess.Popen(
         [sys.executable, str(project_root / "wecker.py")],
         cwd=project_root,
         stdout=subprocess.DEVNULL,
         stderr=subprocess.DEVNULL,
         start_new_session=True,
+        env=env,
     )
 
 
diff --git a/wecker.py b/wecker.py
index a090f7a..782b282 100644
--- a/wecker.py
+++ b/wecker.py
@@ -6,6 +6,9 @@ import random
 import sys
 import os
 import fcntl
+
+# Use PulseAudio/PipeWire audio driver to avoid ALSA device-busy errors.
+os.environ.setdefault("SDL_AUDIODRIVER", "pulse")
 from logging.handlers import RotatingFileHandler
 
 from common import PID_FILE