diff --git a/bin/wally-tool-chain-install.sh b/bin/wally-tool-chain-install.sh
index c52ee485c..a440a5a33 100755
--- a/bin/wally-tool-chain-install.sh
+++ b/bin/wally-tool-chain-install.sh
@@ -151,19 +151,20 @@ sudo make install
 
 cd $RISCV
 opam init -y --disable-sandboxing
-opam switch create ocaml-base-compiler.4.08.0
+opam switch create 5.1.0
 opam install sail -y 
 
 eval $(opam config env)
 git clone https://github.com/riscv/sail-riscv.git
 cd sail-riscv
 # For now, use checkout that is stable for Wally
-git checkout 72b2516d10d472ac77482fd959a9401ce3487f60
+#git checkout 72b2516d10d472ac77482fd959a9401ce3487f60  # not new enough for Zicboz?
 make -j ${NUM_THREADS}
 ARCH=RV32 make -j ${NUM_THREADS}
 sudo ln -sf $RISCV/sail-riscv/c_emulator/riscv_sim_RV64 /usr/bin/riscv_sim_RV64
 sudo ln -sf $RISCV/sail-riscv/c_emulator/riscv_sim_RV32 /usr/bin/riscv_sim_RV32
 
+# riscof
 sudo pip3 install testresources
 pip3 install git+https://github.com/riscv/riscof.git