Tcl8.6

From Eggdrop Wiki

./configure your bot. Open the file config.h in an editor of your choice.

Search for (should be around line 244)

/* Define for Tcl that has threads. */
/* #undef HAVE_TCL_THREADS */

and insert the following right after it

#define USE_INTERP_RESULT 1

Carry on with your make config && make && make install.