diff --git a/mt.1 b/mt.1
index f9062a7..d480659 100644
--- a/mt.1
+++ b/mt.1
@@ -106,7 +106,9 @@ EOF marks at current position.
 .I count
 setmarks at current position (only SCSI tape).
 .IP erase
-Erase the tape.
+Erase the tape. Note that this is a long erase, which on modern
+(high-capacity) tapes can take many hours, and which usually can't be
+aborted.
 .IP status
 Print status information about the tape unit. (If the density code is
 "no translation" in the status output, this does not affect working of the