diff --git a/CHANGELOG.md b/CHANGELOG.md
index f2f86a7256..4e8e8612d9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added day duration slider configuration on map creation UI.
 - Potion of Agility
 - A way for servers to specify must-accept rules for players
+- A flag argument type for commands
 
 ### Changed
 
diff --git a/common/src/cmd.rs b/common/src/cmd.rs
index dc1f318757..fa18862587 100644
--- a/common/src/cmd.rs
+++ b/common/src/cmd.rs
@@ -604,7 +604,9 @@ impl ServerChatCommand {
                 Some(Moderator),
             ),
             ServerChatCommand::Kill => cmd(vec![], "Kill yourself", None),
-            ServerChatCommand::KillNpcs => cmd(vec![], "Kill the NPCs", Some(Admin)),
+            ServerChatCommand::KillNpcs => {
+                cmd(vec![Flag("--also-pets")], "Kill the NPCs", Some(Admin))
+            },
             ServerChatCommand::Kit => cmd(
                 vec![Enum("kit_name", KITS.to_vec(), Required)],
                 "Place a set of items into your inventory.",
@@ -1078,6 +1080,7 @@ impl ServerChatCommand {
                 ArgumentSpec::SubCommand => "{} {/.*/}",
                 ArgumentSpec::Enum(_, _, _) => "{}",
                 ArgumentSpec::Boolean(_, _, _) => "{}",
+                ArgumentSpec::Flag(_) => "{}",
             })
             .collect::<Vec<_>>()
             .join(" ")
@@ -1148,6 +1151,8 @@ pub enum ArgumentSpec {
     /// * suggested tab-completion
     /// * whether it's optional
     Boolean(&'static str, String, Requirement),
+    /// The argument is a flag that enables or disables a feature.
+    Flag(&'static str),
 }
 
 impl ArgumentSpec {
@@ -1224,6 +1229,9 @@ impl ArgumentSpec {
                     format!("[{}]", label)
                 }
             },
+            ArgumentSpec::Flag(label) => {
+                format!("[{}]", label)
+            },
         }
     }
 
@@ -1239,6 +1247,7 @@ impl ArgumentSpec {
             | ArgumentSpec::Message(r)
             | ArgumentSpec::Enum(_, _, r)
             | ArgumentSpec::Boolean(_, _, r) => *r,
+            ArgumentSpec::Flag(_) => Requirement::Optional,
             ArgumentSpec::SubCommand => Requirement::Required,
         }
     }
diff --git a/voxygen/src/cmd.rs b/voxygen/src/cmd.rs
index e5b0e485fc..9dffba8372 100644
--- a/voxygen/src/cmd.rs
+++ b/voxygen/src/cmd.rs
@@ -101,6 +101,7 @@ impl ClientChatCommand {
                 ArgumentSpec::SubCommand => "{} {/.*/}",
                 ArgumentSpec::Enum(_, _, _) => "{}",
                 ArgumentSpec::Boolean(_, _, _) => "{}",
+                ArgumentSpec::Flag(_) => "{}",
             })
             .collect::<Vec<_>>()
             .join(" ")
@@ -595,6 +596,7 @@ impl TabComplete for ArgumentSpec {
                 .filter(|string| string.starts_with(part))
                 .map(|c| c.to_string())
                 .collect(),
+            ArgumentSpec::Flag(part) => vec![part.to_string()],
         }
     }
 }