diff --git a/respodns/ui.py b/respodns/ui.py
index 4398321..206a27a 100644
--- a/respodns/ui.py
+++ b/respodns/ui.py
@@ -19,11 +19,13 @@ def ui(program, args):
     desc = "enable pretty-printing progress to stderr"
     parser.add_argument("--progress", action="store_true", help=desc)
 
+    chkgrp = parser.add_mutually_exclusive_group()
+
     desc = "enable all checks instead of only the most likely ones"
-    parser.add_argument("--all", action="store_true", help=desc)
+    chkgrp.add_argument("--all", action="store_true", help=desc)
 
     desc = "enable only the first check"
-    parser.add_argument("--first", action="store_true", help=desc)
+    chkgrp.add_argument("--first", action="store_true", help=desc)
 
     desc = "enable debugging verbosity"
     parser.add_argument("--debug", action="store_true", help=desc)
@@ -31,9 +33,7 @@ def ui(program, args):
     a = parser.parse_args(args)
 
     checks = [] + chk.first
-    if a.first and a.all:
-        parser.error("--all and --first cannot be used together")
-    elif a.all:
+    if a.all:
         checks += chk.checks
     elif a.first:
         pass