diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index 7f93ef8795308..134f508dfab09 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -778,7 +778,7 @@ extern "system" {
     pub fn ioctlsocket(s: SOCKET, cmd: c_long, argp: *mut c_ulong) -> c_int;
     pub fn InitializeCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
     pub fn EnterCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
-    pub fn TryEnterCriticalSection(CriticalSection: *mut CRITICAL_SECTION) -> BOOLEAN;
+    pub fn TryEnterCriticalSection(CriticalSection: *mut CRITICAL_SECTION) -> BOOL;
     pub fn LeaveCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
     pub fn DeleteCriticalSection(CriticalSection: *mut CRITICAL_SECTION);