diff --git a/event_iocp.c b/event_iocp.c
index 0dd4e904..87ac85dd 100644
--- a/event_iocp.c
+++ b/event_iocp.c
@@ -193,7 +193,7 @@ event_iocp_port_launch(void)
 		++port->n_live_threads;
 	}
 
-	InitializeCriticalSection(&port->lock);
+	InitializeCriticalSectionAndSpinCount(&port->lock, 1000);
 
 	return port;
 err:
diff --git a/evthread_win32.c b/evthread_win32.c
index 995e0e15..655cff83 100644
--- a/evthread_win32.c
+++ b/evthread_win32.c
@@ -38,13 +38,18 @@ struct event_base;
 
 #include "mm-internal.h"
 
+#define SPIN_COUNT 2000
+
 static void *
 evthread_win32_lock_create(unsigned locktype)
 {
 	CRITICAL_SECTION *lock = mm_malloc(sizeof(CRITICAL_SECTION));
 	if (!lock)
 		return NULL;
-	InitializeCriticalSection(lock);
+	if (InitializeCriticalSectionAndSpinCount(lock, SPIN_COUNT) == 0) {
+		mm_free(lock);
+		return NULL;
+	}
 	return lock;
 }