diff --git a/src/hb-private.hh b/src/hb-private.hh
index 179e4e9f7418f487475809ef6449b0ef775d54e3..d58a695c4634dbc8d55a1788486e4d52ffbb001e 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -169,6 +169,7 @@ extern "C" void  hb_free_impl(void *ptr);
 #  if defined(_WIN32_WCE)
      /* Some things not defined on Windows CE. */
 #    define strdup _strdup
+#    define vsnprintf _vsnprintf
 #    define getenv(Name) NULL
 #    if _WIN32_WCE < 0x800
 #      define setlocale(Category, Locale) "C"