@User Install completed, Magic runs on Mac OS Catalina. The key seems to have been to steer the configure away from the TCL/TK (Version 8.5) installed in /usr/local. I used MacPorts to get the latest TCL and TK, and these installed in their MacPorts standard location of /opt/local/ Thus the configure command for me is: ./configure --x-includes=/opt/X11/include --x-libraries=/opt/X11/lib --with-tcl=/opt/local/lib --with-tk=/opt/local/lib --with-tclincls=/opt/local/include --with-tkincls=/opt/local/include --with-tcllibs=/opt/local/lib --with-tklibs=/opt/local/lib Then the modification to the CFLAGS line in the defs.mak file is to append these flags: -Wno-error=implicit-function-declaration -Wno-error=return-typ Then "make" and "sudo make install" proceed normally and the install completes. I should add that when I updated the TCL/TK to the latest 8.6, I no longer saw even warnings in the make process. So that may have been the core problem, and the addition to the CFLAGS flags might be unnecessary. And finally, here's what I'm supposed to see when I invoke the first tutorial in Magic: