diff --git a/calendar/teachingdates/config/cli.py b/calendar/teachingdates/config/cli.py
index 472a24c..0966b42 100644
--- a/calendar/teachingdates/config/cli.py
+++ b/calendar/teachingdates/config/cli.py
@@ -18,15 +18,22 @@
         raise TypeError("expected list, got {t}".format(t=str(type(words))))
 
 
-def switch_message(switches, context, severity="warning", required=False):
+def switch_message(switches, context, required=False):
     switch_string = oxford_comma_list(switches)
-    return ("{prog}: {severity}: {switches} {verb} {required} for "
-            "{context}".format(prog=PROG,
-                               severity=severity,
-                               switches=switch_string,
-                               verb="are" if len(switches) > 1 else "is",
-                               required="required" if required else "ignored",
-                               context=context))
+    return ("{switches} {verb} {required} for {context}".format(
+                switches=switch_string,
+                verb="are" if len(switches) > 1 else "is",
+                required="required" if required else "ignored",
+                context=context))
+
+
+def warning(message):
+    # This is somewhat trivial, but does provide output equivalence
+    # with parser.error().
+    print("{prog}: warning: {message}".format(
+        prog=PROG,
+        message=message
+    ))
 
 
 def parse_command_line():
@@ -127,37 +134,46 @@
     args.style = style_map[args.style]
 
     if args.style == "calendar":
+        # --teaching-period is required
+        if not args.period:
+            parser.error(switch_message(
+                ["--teaching-period/-t"],
+                context="'{style}' style".format(style=args.style),
+                required=True))
         # --paper is irrelevant
         if args.paper:
             args.paper = ""
-            print("{prog}: warning: --paper/-p is ignored for 'calendar' "
-                  "style".format(prog=PROG))
-        # --teaching-period is required
-        if not args.period:
-            parser.exit(
-                2, "{prog}: error: --teaching-period/-t is required for "
-                "'calendar' style\n".format(prog=PROG))
+            warning(switch_message(
+                ["--paper/-p"],
+                context="'{style}' style".format(style=args.style)
+            ))
 
     elif args.style == "iso":
         # both --paper and --teaching-period are irrelevant
-        if args.paper or args.period:
+        if any([args.paper, args.period]):
             args.paper = ""
             args.period = "iso"
-            print("{prog}: warning: --paper/-p and --teaching-period/-t are "
-                  "ignored for 'iso' style".format(prog=PROG))
+            warning(switch_message(
+                ["--paper/-p", "--teaching-period/-t"],
+                context="'{style}' style".format(style=args.style)
+            ))
 
-    elif args.style == "lecture":
+    elif args.style in ["lecture", "lab"]:
+        # both --paper and --teaching-period are required
+        if not all([args.paper, args.period]):
+            parser.error(switch_message(
+                ["-paper/-p", "--teaching-period/-t"],
+                context="'{style}' style".format(style=args.style),
+                required=True
+            ))
         # --end-of-week is irrelevant
         if args.end_of_week is not None:
             args.end_of_week = None
-            print("{prog}: warning: --end-of-week/-e is ignored for 'lecture' "
-                  "style".format(prog=PROG))
-        # both --paper and --teaching-period are required
-        if not args.paper:
-            parser.exit(
-                2,
-                message="{prog}: error: -paper/-p and --teaching-period/-t "
-                "are required for 'lecture' style\n".format(prog=PROG))
+            warning(switch_message(
+                ["--end-of-week/-e"],
+                context="'{style}' style".format(style=args.style)
+            ))
+            # ignored_args(["--end-of-week/-e"], args.style))
 
     else:
         pass