diff --git a/macos.md b/macos.md
index d8aa2dc..3609272 100644
--- a/macos.md
+++ b/macos.md
@@ -1,9 +1,26 @@
 
-# Instructions for getting the build running on MacOS
+# Instructions for getting the build of the security monitor running on MacOS
 
-1. Install the Risc-V toolchain.
 
-2. environment variables
-    TODO see diff
+1. Install basic dependencies.
+```
+brew install coreutils  # to have nproc available
+brew install autoconf automake curl python libmpc mpfr gmp gawk flex texinfo libtool bc expat # for OpenSBI build
+```
 
-3. 
+2. Install the Risc-V toolchain.
+```
+# https://github.com/riscv-software-src/homebrew-riscv
+brew tap riscv-software-src/riscv
+brew install riscv-gnu-toolchain
+```
+
+3. Source environment variables.
+```
+source macos_env
+```
+
+4. Build the security monitor:
+```
+make security_monitor
+```
diff --git a/macos_env b/macos_env
index 7dd2445..fc51cd6 100644
--- a/macos_env
+++ b/macos_env
@@ -3,5 +3,3 @@ export RISCV_GNU_TOOLCHAIN_WORK_DIR=/opt/homebrew/Cellar/riscv-gnu-toolchain/mai
 
 export PATH=$RISCV_GNU_TOOLCHAIN_WORK_DIR/bin:$PATH
 export CROSS_COMPILE=riscv64-unknown-elf-
-alias nproc="sysctl -n hw.logicalcpu"
-
diff --git a/security-monitor/rust-crates/opensbi.sh b/security-monitor/rust-crates/opensbi.sh
index 6547141..ec660d4 100755
--- a/security-monitor/rust-crates/opensbi.sh
+++ b/security-monitor/rust-crates/opensbi.sh
@@ -35,7 +35,7 @@ cd ${OPENSBI_SOURCE_DIR}/
 git reset --hard
 find $PATCH_DIR -type f -name '*.patch' -print0 | xargs -0 git apply
 
-make CROSS_COMPILE=${CROSS_COMPILE} O=${WORK_DIR} PLATFORM=generic -j$(sysctl -n hw.logicalcpu) 
+make CROSS_COMPILE=${CROSS_COMPILE} O=${WORK_DIR} PLATFORM=generic -j$(nproc)
 make CROSS_COMPILE=${CROSS_COMPILE} I=${WORK_DIR} PLATFORM=generic install
 
 echo "done"