diff --git a/CDDB.py b/CDDB.py
index 7694314..327d663 100644
--- a/CDDB.py
+++ b/CDDB.py
@@ -18,7 +18,7 @@ version = 2.0
 if 'EMAIL' in os.environ:
     (default_user, hostname) = os.environ['EMAIL'].split('@')
 else:
-    default_user = os.environ['USER'] or os.geteuid() or 'user'
+    default_user = os.environ.get('USER') or os.geteuid() or 'user'
     hostname = socket.gethostname() or 'host'
 
 proto = 6
diff --git a/common.py b/common.py
index 985006b..95ab52b 100644
--- a/common.py
+++ b/common.py
@@ -1,5 +1,19 @@
 import os
-import discid
+import logging
+
+try:
+    from config import APP_NAME as ROOT_LOGGER_NAME
+except ImportError:
+    ROOT_LOGGER_NAME = 'root'
+logger = logging.getLogger(ROOT_LOGGER_NAME).getChild(__name__)
+
+# make module usable without discid dependency
+try:
+    import discid
+except ModuleNotFoundError:
+    logger.warning("Python module discid not installed")
+except OSError:
+    logger.exception("You might install python3-libdiscid")
 
 KEY_ALBUM = 'album'
 KEY_APERTURE = 'aperture'
diff --git a/metadata.py b/metadata.py
index a15254a..1a0f125 100644
--- a/metadata.py
+++ b/metadata.py
@@ -14,8 +14,12 @@ try:
 except ImportError:
     ROOT_LOGGER_NAME = 'root'
 logger = logging.getLogger(ROOT_LOGGER_NAME).getChild(__name__)
+
+# make module usable without discid dependency
 try:
     import discid
+except ModuleNotFoundError:
+    logger.warning("Python module discid not installed")
 except OSError:
     logger.exception("You might install python3-libdiscid")