diff --git a/vm/os-unix.cpp b/vm/os-unix.cpp
index 075ceff421..f47dc1d363 100644
--- a/vm/os-unix.cpp
+++ b/vm/os-unix.cpp
@@ -47,15 +47,13 @@ u64 system_micros()
 	return (u64)t.tv_sec * 1000000 + t.tv_usec;
 }
 
-void sleep_micros(cell usec)
-{
-	usleep(usec);
-}
-
-void sleep_nanos(timespec ts)
+void sleep_nanos(u64 nsec)
 {
+	timespec ts;
 	timespec ts_rem;
 	int ret;
+	ts.tv_sec = nsec / 1000000000;
+	ts.tv_nsec = nsec % 1000000000;
 	ret = nanosleep(&ts,&ts_rem);
 	while(ret == -1 && errno == EINTR)
 	{
diff --git a/vm/os-unix.hpp b/vm/os-unix.hpp
index 40d1255c8c..fa9bc71417 100644
--- a/vm/os-unix.hpp
+++ b/vm/os-unix.hpp
@@ -54,8 +54,7 @@ void dump_stack_signal(int signal, siginfo_t* siginfo, void* uap);
 
 u64 system_micros();
 u64 nano_count();
-void sleep_micros(cell usec);
-void sleep_nanos(cell nsec);
+void sleep_nanos(u64 nsec);
 
 void init_platform_globals();
 
diff --git a/vm/os-windows.cpp b/vm/os-windows.cpp
index 773e40fbba..8a7cf9024b 100755
--- a/vm/os-windows.cpp
+++ b/vm/os-windows.cpp
@@ -126,14 +126,9 @@ segment::~segment()
 		fatal_error("Segment deallocation failed",0);
 }
 
-void factor_vm::sleep_micros(u64 usec)
+void sleep_nanos(u64 nsec)
 {
-	Sleep((DWORD)(usec / 1000));
-}
-
-void factor_vm::sleep_nanos(u64 nsec)
-{
-	Sleep((DWORD)(nsec / 1000000));
+	Sleep((DWORD)(nsec/1000000));
 }
 
 long getpagesize()
diff --git a/vm/run.cpp b/vm/run.cpp
index 9203dcf1e9..ebe3678439 100755
--- a/vm/run.cpp
+++ b/vm/run.cpp
@@ -20,7 +20,7 @@ void factor_vm::primitive_nano_count()
 
 void factor_vm::primitive_sleep()
 {
-	sleep_micros(to_cell(dpop()));
+	sleep_nanos(factor_vm::to_unsigned_8(dpop()));
 }
 
 }
diff --git a/vm/vm.hpp b/vm/vm.hpp
index 4f2544db25..04eaf3d2ef 100755
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -674,7 +674,6 @@ struct factor_vm
 
 	// os-windows
   #if defined(WINDOWS)
-	void sleep_micros(u64 usec);
 	void sleep_nanos(u64 nsec);
 	const vm_char *vm_executable_path();
 	const vm_char *default_image_path();