diff --git a/alibuild_helpers/args.py b/alibuild_helpers/args.py
index 7d8d4141..49c61196 100644
--- a/alibuild_helpers/args.py
+++ b/alibuild_helpers/args.py
@@ -14,11 +14,11 @@
 from os.path import abspath, dirname, basename
 import sys
 
-# Default workdir: fall back on "sw" if env is not set
-DEFAULT_WORK_DIR = os.environ.get("ALIBUILD_WORK_DIR", os.environ.get("ALICE_WORK_DIR", "sw"))
+# Default workdir: fall back on "sw" if env is not set or empty
+DEFAULT_WORK_DIR = os.environ.get("ALIBUILD_WORK_DIR") or os.environ.get("ALICE_WORK_DIR") or "sw"
 
 # cd to this directory before start
-DEFAULT_CHDIR = os.environ.get("ALIBUILD_CHDIR", ".")
+DEFAULT_CHDIR = os.environ.get("ALIBUILD_CHDIR") or "."
 
 def csv_list(s):
   return s.split(',')
diff --git a/alibuild_helpers/doctor.py b/alibuild_helpers/doctor.py
index e0295348..0415e112 100644
--- a/alibuild_helpers/doctor.py
+++ b/alibuild_helpers/doctor.py
@@ -94,7 +94,7 @@ def doctorArgParser(parser):
   parser.add_argument("--docker-image", dest="dockerImage",
                       help="Image to use in case you build with docker (implies --docker)")
   parser.add_argument("--chdir", "-C", help="Change to the specified directory first",
-                      metavar="DIR", dest="chdir", default=os.environ.get("ALIBUILD_CHDIR", "."))
+                      metavar="DIR", dest="chdir", default=os.environ.get("ALIBUILD_CHDIR") or ".")
   return parser
 
 def doDoctor(args, parser):