diff --git a/prepare-vms/map-dns.py b/prepare-vms/map-dns.py
index 95fee748..1d25eee9 100755
--- a/prepare-vms/map-dns.py
+++ b/prepare-vms/map-dns.py
@@ -2,11 +2,11 @@
 """
 There are two ways to use this script:
 
-1. Pass a tag name as a single argument.
-It will then take the clusters corresponding to that tag, and assign one
-domain name per cluster. Currently it gets the domains from a hard-coded
-path. There should be more domains than clusters.
-Example: ./map-dns.py 2020-08-15-jp
+1. Pass a file name and a tag name as a single argument.
+It will load a list of domains from the given file (one per line),
+and assign them to the clusters corresponding to that tag.
+There should be more domains than clusters.
+Example: ./map-dns.py domains.txt 2020-08-15-jp
 
 2. Pass a domain as the 1st argument, and IP addresses then.
 It will configure the domain with the listed IP addresses.
@@ -19,55 +19,53 @@ import requests
 import sys
 import yaml
 
-# configurable stuff
-domains_file = "../../plentydomains/domains.txt"
+# This can be tweaked if necessary.
 config_file = os.path.join(
-	os.environ["HOME"], ".config/gandi/config.yaml")
-tag = None
+  os.environ["HOME"], ".config/gandi/config.yaml")
 apiurl = "https://dns.api.gandi.net/api/v5/domains"
-
-if len(sys.argv) == 2:
-	tag = sys.argv[1]
-	domains = open(domains_file).read().split()
-	domains = [ d for d in domains if not d.startswith('#') ]
-	ips = open(f"tags/{tag}/ips.txt").read().split()
-	settings_file = f"tags/{tag}/settings.yaml"
-	clustersize = yaml.safe_load(open(settings_file))["clustersize"]
-else:
-	domains = [sys.argv[1]]
-	ips = sys.argv[2:]
-	clustersize = len(ips)
-
-# inferred stuff
 apikey = yaml.safe_load(open(config_file))["apirest"]["key"]
 
-# now do the fucking work
-while domains and ips:
-	domain = domains[0]
-	domains = domains[1:]
-	cluster = ips[:clustersize]
-	ips = ips[clustersize:]
-	print(f"{domain} => {cluster}")
-	zone = ""
-	node = 0
-	for ip in cluster:
-		node += 1
-		zone += f"@ 300 IN A {ip}\n"
-		zone += f"* 300 IN A {ip}\n"
-		zone += f"node{node} 300 IN A {ip}\n"
-	r = requests.put(
-		f"{apiurl}/{domain}/records",
-		headers={"x-api-key": apikey},
-		data=zone)
-	print(r.text)
+# Figure out if we're called for a bunch of domains, or just one.
+first_arg = sys.argv[1]
+if os.path.isfile(first_arg):
+  domains = open(first_arg).read().split()
+  domains = [ d for d in domains if not d.startswith('#') ]
+  tag = sys.argv[2]
+  ips = open(f"tags/{tag}/ips.txt").read().split()
+  settings_file = f"tags/{tag}/settings.yaml"
+  clustersize = yaml.safe_load(open(settings_file))["clustersize"]
+else:
+  domains = [first_arg]
+  ips = sys.argv[2:]
+  clustersize = len(ips)
 
-	#r = requests.get(
-	#	f"{apiurl}/{domain}/records",
-	#	headers={"x-api-key": apikey},
-	#	)
+# Now, do the work.
+while domains and ips:
+  domain = domains[0]
+  domains = domains[1:]
+  cluster = ips[:clustersize]
+  ips = ips[clustersize:]
+  print(f"{domain} => {cluster}")
+  zone = ""
+  node = 0
+  for ip in cluster:
+    node += 1
+    zone += f"@ 300 IN A {ip}\n"
+    zone += f"* 300 IN A {ip}\n"
+    zone += f"node{node} 300 IN A {ip}\n"
+  r = requests.put(
+    f"{apiurl}/{domain}/records",
+    headers={"x-api-key": apikey},
+    data=zone)
+  print(r.text)
+
+  #r = requests.get(
+  #  f"{apiurl}/{domain}/records",
+  #  headers={"x-api-key": apikey},
+  #  )
 
 if domains:
-	print(f"Good, we have {len(domains)} domains left.")
+  print(f"Good, we have {len(domains)} domains left.")
 
 if ips:
-	print(f"Crap, we have {len(ips)} IP addresses left.")
+  print(f"Crap, we have {len(ips)} IP addresses left.")