diff -r 7c333cffd63e -r 184584b82c4c hedgewars/uChat.pas
--- a/hedgewars/uChat.pas	Fri Oct 05 04:00:16 2018 +0200
+++ b/hedgewars/uChat.pas	Fri Oct 05 04:17:56 2018 +0200
@@ -465,6 +465,12 @@
 
 if (s[1] = '/') then
     begin
+    if (Length(s) <= 1) then
+        begin
+        // empty chat command
+        AddChatString(#0 + trcmd[sidCmdUnknown]);
+        exit;
+        end;
 
     // Ignore message-type commands with empty argument list
     if (copy(s, 2, 2) = 'me') and (Length(s) = 3) then