diff --git a/visidata/threads.py b/visidata/threads.py
index <HASH>..<HASH> 100644
--- a/visidata/threads.py
+++ b/visidata/threads.py
@@ -380,6 +380,7 @@ def codestr(code):
     return code.co_name
 
 ThreadsSheet.addCommand('^C', 'cancel-thread', 'cancelThread(cursorRow)', 'abort thread at current row')
+ThreadsSheet.addCommand(None, 'add-row', 'fail("cannot add new rows on Threads Sheet")', 'invalid command')
 
 
 ProfileSheet.addCommand('z^S', 'save-profile', 'source.dump_stats(input("save profile to: ", value=name+".prof"))', 'save profile')
[threads] disable add-row on ThreadsSheet #<I>