diff --git a/ag.cc b/ag.cc
index b8b41fd..53230ef 100644
--- a/ag.cc
+++ b/ag.cc
@@ -10,6 +10,9 @@
 #include <string>
 #include <GL/gl.h>
 #include <GL/glu.h>
+#ifdef _WIN32
+#include <windows.h>                /* Sleep() */
+#endif
 using namespace std;
 
 namespace ag
@@ -157,7 +160,11 @@ namespace ag
             if (lua_type(L, -1) == LUA_TNUMBER)
             {
                 double seconds = lua_tonumber(L, -1);
+#ifdef _WIN32
+                Sleep((DWORD)(seconds * 1000));
+#else
                 usleep((useconds_t) (seconds * 1000000));
+#endif
             }
         }