diff --git a/CMakeLists.txt b/CMakeLists.txt
index 33bc1ede..cf46f844 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -222,7 +222,6 @@ set(STA_SOURCE
   util/Error.cc
   util/Fuzzy.cc
   util/Hash.cc
-  util/Machine.cc
   util/MinMax.cc
   util/PatternMatch.cc
   util/Report.cc
@@ -239,6 +238,16 @@ set(STA_SOURCE
   verilog/VerilogWriter.cc
   )
 
+if(APPLE)
+  list(APPEND STA_SOURCE util/MachineApple.cc)
+elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+  list(APPEND STA_SOURCE util/MachineLinux.cc)
+elseif(WIN32)
+  list(APPEND STA_SOURCE util/MachineWin32.cc)
+else()
+  list(APPEND STA_SOURCE util/MachineUnknown.cc)
+endif()
+
 # Source files.
 set(STA_TCL_FILES
   tcl/Init.tcl
diff --git a/util/MachineWin32.cc b/util/MachineWin32.cc
index b2def31d..2c2c36bf 100644
--- a/util/MachineWin32.cc
+++ b/util/MachineWin32.cc
@@ -24,6 +24,7 @@
 
 #include "Machine.hh"
 
+#include <cstdarg>
 #include <cstdio>
 #include <windows.h> // GetSystemInfo