tcl headers not found while installing openSTA

This is what i get after executing cmake ..

 - TCL library: /usr/lib/x86_64-linux-gnu/libtcl8.6.so
-- TCL header: TCL_HEADER-NOTFOUND

and after executing "make" 
fatal error: tcl.h: No such file or directory
   19 | #include <tcl.h>

sudo apt install tcl-dev