diff --git a/vlib/builtin/cfns.v b/vlib/builtin/cfns.v
index 063f16d43f..c82a3bc819 100644
--- a/vlib/builtin/cfns.v
+++ b/vlib/builtin/cfns.v
@@ -144,8 +144,21 @@ fn C.FindClose()
 fn C.MAKELANGID() int
 fn C.FormatMessage() voidptr
 fn C.CloseHandle()
-fn C.WaitForSingleObject()
 fn C.GetExitCodeProcess()
 fn C.RegOpenKeyEx() voidptr
 fn C.GetTickCount() i64
-fn C.Sleep()
\ No newline at end of file
+
+fn C.Sleep()
+fn C.WSAStartup(u16, &voidptr) int
+fn C.WSAGetLastError() int
+fn C.closesocket(int) int
+fn C.vschannel_init(&C.TlsContext)
+fn C.request(&C.TlsContext,int, &u16, byteptr, &byteptr)
+fn C.vschannel_cleanup(&C.TlsContext)
+fn C.URLDownloadToFile(int, &u16,&u16, int, int)
+fn C.GetLastError() u32
+fn C.CreateDirectory(byteptr, int) bool
+fn C.BCryptGenRandom(int,voidptr,int,int) int
+fn C.CreateMutex(int,bool,byteptr) voidptr
+fn C.WaitForSingleObject(voidptr,int) int
+fn C.ReleaseMutex(voidptr) bool
\ No newline at end of file
diff --git a/vlib/os/os.v b/vlib/os/os.v
index 2e12419f6f..397855d242 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -67,7 +67,7 @@ fn C.ftell(fp voidptr) int
 fn C.getenv(byteptr) byteptr
 fn C.sigaction(int, voidptr, int)
 
-fn C.GetLastError() u32
+
 
 // read_bytes reads an amount of bytes from the beginning of the file
 pub fn (f File) read_bytes(size int) []byte {
diff --git a/vlib/os/os_windows.v b/vlib/os/os_windows.v
index af18ae9f19..33a3dd1a4a 100644
--- a/vlib/os/os_windows.v
+++ b/vlib/os/os_windows.v
@@ -130,7 +130,7 @@ pub fn dir_exists(path string) bool {
 	return false
 }
 
-fn C.CreateDirectory(byteptr, int) bool
+
 
 // mkdir creates a new directory with the specified path.
 pub fn mkdir(path string) ?bool {
diff --git a/vlib/sync/sync_windows.v b/vlib/sync/sync_windows.v
index 9ed1113472..74aa807960 100644
--- a/vlib/sync/sync_windows.v
+++ b/vlib/sync/sync_windows.v
@@ -77,7 +77,7 @@ pub fn (m mut Mutex) lock() {
 
 pub fn (m mut Mutex) unlock() {
 	if m.state == .waiting {
-		if C.ReleaseMutex(m.mx) != 0 {
+		if ReleaseMutex(m.mx) {
 			m.state = .broken
 			return
 		}