diff --git a/sbin/ipfw/ipfw.8 b/sbin/ipfw/ipfw.8
index d8c2bc5709ef..391e0a65c2d7 100644
--- a/sbin/ipfw/ipfw.8
+++ b/sbin/ipfw/ipfw.8
@@ -2516,3 +2516,7 @@ or similar system calls.
 Rules which use uid, gid or jail based matching should be used only
 if debug.mpsafenet=0 to avoid possible deadlocks due to layering
 violations in its implementation.
+.Pp
+Rule syntax is subject to the command line environment and some patterns
+may need to be escaped with the backslash character
+or quoted appropriately.