diff --git a/pyazhpc/azconfig.py b/pyazhpc/azconfig.py
index e9f201a1..d0ca2a32 100644
--- a/pyazhpc/azconfig.py
+++ b/pyazhpc/azconfig.py
@@ -22,7 +22,7 @@ class ConfigFile:
             json.dump(self.data, f, indent=4)
 
     def get_install_from_destination(self):
-        install_from = self.read_value("install_from", None)
+        install_from = self.read_value("install_from")
         dest = install_from
         if install_from is not None:
             if self.read_value(f"resources.{install_from}.public_ip", False):
@@ -97,13 +97,9 @@ class ConfigFile:
             else:
                 res = it
         except KeyError:
-            if default is not None:
-                log.debug(f"using default value ({default})")
-                res = default
-            else:
-                log.error("read_value : "+v+" not in config")
-                sys.exit(1)
-
+            log.debug(f"using default value ({default})")
+            res = default
+        
         log.debug("read_value (exit): "+v+"="+str(res))
 
         return res
diff --git a/pyazhpc/azhpc.py b/pyazhpc/azhpc.py
index f70b4a8c..21c81167 100644
--- a/pyazhpc/azhpc.py
+++ b/pyazhpc/azhpc.py
@@ -111,7 +111,7 @@ def do_scp(args):
     sshkey="{}_id_rsa".format(adminuser)
     # TODO: check ssh key exists
 
-    jumpbox = c.read_value("install_from", None)
+    jumpbox = c.read_value("install_from")
     if jumpbox == None:
         log.error(f"Missing 'install_from' property")
         sys.exit(1)
@@ -148,7 +148,7 @@ def do_connect(args):
     else:
         sshuser = args.user
 
-    jumpbox = c.read_value("install_from", None)
+    jumpbox = c.read_value("install_from")
     if jumpbox == None:
         log.error(f"Missing 'install_from' property")
         sys.exit(1)
@@ -234,7 +234,7 @@ def do_status(args):
     adminuser = c.read_value("admin_user")
     ssh_private_key="{}_id_rsa".format(adminuser)
 
-    jumpbox = c.read_value("install_from", None)
+    jumpbox = c.read_value("install_from")
     if jumpbox == None:
         log.error(f"Missing 'install_from' property")
         sys.exit(1)
@@ -260,7 +260,7 @@ def do_run(args):
     else:
         sshuser = args.user
 
-    jumpbox = c.read_value("install_from", None)
+    jumpbox = c.read_value("install_from")
     if jumpbox == None:
         log.error(f"Missing 'install_from' property")
         sys.exit(1)
@@ -271,7 +271,7 @@ def do_run(args):
     hosts = []
     if args.nodes:
         for r in args.nodes.split(" "):
-            rtype = c.read_value(f"resources.{r}.type", None)
+            rtype = c.read_value(f"resources.{r}.type")
             if not rtype:
                 log.error(f"resource {r} does not exist in config")
                 sys.exit(1)
@@ -420,7 +420,7 @@ def do_build(args):
     log.info("building install scripts")
     azinstall.generate_install(config, tmpdir, adminuser, private_key_file, public_key_file)
     
-    jumpbox = c.read_value("install_from", None)
+    jumpbox = c.read_value("install_from")
     if jumpbox == None:
         log.info("nothing to install ('install_from' is not set)")
     else: