Can't seem to build for Fedora 36

I have installed (I think) all of the needed dev libraries but when I try to install on my Fedora 36 installation, I get errors. Such as:

if test -f /home/cbmeeks/flexprop/Makefile; then echo "ERROR: Install directory contains a Makefile (possibly installing to original source)"; exit 1; fi
(make -C board/sdcard P2CC="`pwd`/bin/flexspin -2 -I`pwd`/spin2cpp/include")
make[1]: Entering directory '/home/cbmeeks/tmp/flexprop/board/sdcard'
/home/cbmeeks/tmp/flexprop/bin/flexspin -2 -I/home/cbmeeks/tmp/flexprop/spin2cpp/include -o sdboot.binary sdboot.c ff.c sdmm.c
Propeller Spin/PASM Compiler 'FlexSpin' (c) 2011-2022 Total Spectrum Software Inc.
Version 5.9.18-HEAD-v5.9.18 Compiled on: Oct 28 2022
sdboot.c
ff.c
sdmm.c
posixio.c
fputs.c
fmt.c
errno.c
sdboot.p2asm
Done.
Program size is 25704 bytes
make[1]: Leaving directory '/home/cbmeeks/tmp/flexprop/board/sdcard'
rm -f board/sdcard/*.p2asm
mv board/sdcard/sdboot.binary board/P2ES_sdcard.bin
mkdir -p flexprop/bin
mkdir -p flexprop/doc
mkdir -p flexprop/board
cp -r README.md License.txt samples src flexprop
cp -r spin2cpp/doc/* flexprop/doc
cp -r spin2cpp/Changelog.txt flexprop/doc/Changelog-compiler.txt
cp -r Changelog.txt flexprop/doc/Changelog-gui.txt
cp -r loadp2/README.md flexprop/doc/loadp2.md
cp -r loadp2/LICENSE flexprop/doc/loadp2.LICENSE.txt
cp -r spin2cpp/COPYING.LIB flexprop/doc/COPYING.LIB
cp -r spin2cpp/include flexprop/
cp -r doc/*.txt flexprop/doc
cp -r board/* flexprop/board
cc  -o flexprop.bin src/flexprop_native.c src/p2debug.c -I/usr/include/tcl8.6 -ltk8.6 -ltcl8.6 -lfontconfig -lXft -lXss -lXext -lX11 -lz -ldl -lpthread -lm
/usr/bin/ld: cannot find -lXss
collect2: error: ld returned 1 exit status
make: *** [Makefile:135: flexprop.bin] Error 1

I'm not sure where to go from here. Any ideas on what I could try next?

Thanks

totalspectrum / flexprop

Can't seem to build for Fedora 36 #59