diff --git a/runtime/doc/if_tcl.txt b/runtime/doc/if_tcl.txt
index 685c3c2..a02c8c5 100644
--- a/runtime/doc/if_tcl.txt
+++ b/runtime/doc/if_tcl.txt
@@ -54,6 +54,9 @@
 	EOF
 	endfunction
 <
+To see what version of Tcl you have: >
+	:tcl puts [info patchlevel]
+<
 
 							*:tcldo* *:tcld*
 :[range]tcld[o] {cmd}	Execute Tcl command {cmd} for each line in [range]