diff --git a/src/hb-mutex-private.hh b/src/hb-mutex-private.hh
index 628120195..a8ea39ccf 100644
--- a/src/hb-mutex-private.hh
+++ b/src/hb-mutex-private.hh
@@ -47,7 +47,11 @@
 #include <windows.h>
 typedef CRITICAL_SECTION hb_mutex_impl_t;
 #define HB_MUTEX_IMPL_INIT	{0}
+#if defined(WINAPI_FAMILY) && (WINAPI_FAMILY==WINAPI_FAMILY_PC_APP || WINAPI_FAMILY==WINAPI_FAMILY_PHONE_APP)
+#define hb_mutex_impl_init(M)	InitializeCriticalSectionEx (M, 0, 0)
+#else
 #define hb_mutex_impl_init(M)	InitializeCriticalSection (M)
+#endif
 #define hb_mutex_impl_lock(M)	EnterCriticalSection (M)
 #define hb_mutex_impl_unlock(M)	LeaveCriticalSection (M)
 #define hb_mutex_impl_finish(M)	DeleteCriticalSection (M)
diff --git a/src/hb-private.hh b/src/hb-private.hh
index c92cdec51..8438fae7a 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -142,6 +142,8 @@
 #define getenv(Name) NULL
 #define setlocale(Category, Locale) "C"
 static int errno = 0; /* Use something better? */
+#elif defined(WINAPI_FAMILY) && (WINAPI_FAMILY==WINAPI_FAMILY_PC_APP || WINAPI_FAMILY==WINAPI_FAMILY_PHONE_APP)
+#define getenv(Name) NULL
 #endif
 
 #if HAVE_ATEXIT