diff --git a/lib/make.rb b/lib/make.rb
index be1d190..e36943f 100644
--- a/lib/make.rb
+++ b/lib/make.rb
@@ -56,7 +56,9 @@ module Make
             @steps = makefile["steps"] || []
 
             @environment = ENV.to_h.merge(
-                "PREFIX" => get_prefix
+                "PREFIX" => get_prefix,
+                "CPUS" => System.cpus.to_s,
+                "SUDO" => (@target == :user ? "" : "sudo")
             )
 
             environment = makefile["environment"]
@@ -69,13 +71,22 @@ module Make
         end
 
         def get_prefix
+            sys_prefix = case System.os_name
+            when :macos
+                "/usr"
+            else
+                ""
+            end
+
             case @target
             when :user
                 "#{ENV["HOME"]}/.local"
             when :package
-                "/pkg/#{@name}/#{@repository.branch}"
+                "#{sys_prefix}/pkg/#{@name}/#{@repository.branch}"
             when :system
-                "/"
+                "#{sys_prefix}/"
+            else
+                raise "Unknown target: #{@target.inspect}"
             end
         end
 
diff --git a/lib/system/debian.rb b/lib/system/debian.rb
index 61170c8..6504a2f 100644
--- a/lib/system/debian.rb
+++ b/lib/system/debian.rb
@@ -1,8 +1,15 @@
+require 'open3'
+
 module DebianSystem
   def os_name
     "Debian Linux"
   end
 
+  def cpus
+    stdout, stderr, status = Open3.capture3("nproc")
+    stdout.strip.to_i
+  end
+
   def install(packages)
     missing_packages = packages.reject { |pkg| package_installed?(pkg) }
 
diff --git a/lib/system/macos.rb b/lib/system/macos.rb
index 7cacd3d..b2a6a22 100644
--- a/lib/system/macos.rb
+++ b/lib/system/macos.rb
@@ -1,8 +1,15 @@
+require 'open3'
+
 module MacOSSystem
   def os_name
     "macOS"
   end
 
+  def cpus
+    stdout, stderr, status = Open3.capture3("sysctl -n hw.ncpu")
+    stdout.strip.to_i
+  end
+
   def install(packages)
     missing_packages = packages.reject { |pkg| package_installed?(pkg) }
 
diff --git a/recipes/dry-run.yml b/recipes/dry-run.yml
index f5258b5..77e8509 100644
--- a/recipes/dry-run.yml
+++ b/recipes/dry-run.yml
@@ -9,7 +9,7 @@ repository:
   branch: main
 
 steps:
-  - echo installing in $PREFIX
+  - echo installing in $PREFIX and cpus $CPUS
   - cd $WORK_DIR
   - ls