diff --git a/doc/CHANGELOG b/doc/CHANGELOG
index e6f4f64..a864353 100644
--- a/doc/CHANGELOG
+++ b/doc/CHANGELOG
@@ -3,6 +3,7 @@ Auto IRC Bot 3.0: Change Log
 
 3.0 Indev
 ===============================================================================
+    * Added API::IRC::ison for checking if a user is on a channel.
     * Werewolf: Fixed a bug in harlot staying home.
     * Werewolf: Various bug fixes.
     * Werewolf 1.06: Fixed an annoyance and added traitor transformation.
diff --git a/lib/API/IRC.pm b/lib/API/IRC.pm
index be7b4b6..00e28e1 100644
--- a/lib/API/IRC.pm
+++ b/lib/API/IRC.pm
@@ -9,7 +9,7 @@ use Exporter;
 use base qw(Exporter);
 
 our @EXPORT_OK = qw(ban cjoin cpart cmode umode kick privmsg notice quit nick names
-                    topic who usrc match_mask);
+                    topic who usrc match_mask ison);
 
 # Create the on_disconnect event.
 API::Std::event_add('on_disconnect');
@@ -130,6 +130,17 @@ sub act {
     return 1;
 }
 
+# Check if a given nickname is on a channel.
+sub ison {
+    my ($svr, $chan, $nick) = @_;
+
+    if (!exists $State::IRC::chanusers{$svr}) { return }
+    if (!exists $State::IRC::chanusers{$svr}{$chan}) { return }
+    if (!exists $State::IRC::chanusers{$svr}{$chan}{lc $nick}) { return }
+
+    return 1;
+}
+
 # Change bot nickname.
 sub nick {
     my ($svr, $newnick) = @_;