Index: lib/msan/msan_interceptors.cc
===================================================================
--- lib/msan/msan_interceptors.cc
+++ lib/msan/msan_interceptors.cc
@@ -531,7 +531,7 @@
 INTERCEPTOR(wchar_t *, wmemset, wchar_t *s, wchar_t c, SIZE_T n) {
   CHECK(MEM_IS_APP(s));
   ENSURE_MSAN_INITED();
-  wchar_t *res = (wchar_t *)REAL(memset)(s, c, n * sizeof(wchar_t));
+  wchar_t *res = REAL(wmemset)(s, c, n);
   __msan_unpoison(s, n * sizeof(wchar_t));
   return res;
 }
Index: lib/msan/tests/msan_test.cc
===================================================================
--- lib/msan/tests/msan_test.cc
+++ lib/msan/tests/msan_test.cc
@@ -1834,6 +1834,16 @@
   EXPECT_POISONED(buff[2]);
 }
 
+TEST(MemorySanitizer, wmemset) {
+    wchar_t x[25];
+    break_optimization(x);
+    EXPECT_POISONED(x[0]);
+    wmemset(x, L'A', 10);
+    EXPECT_EQ(x[0], L'A');
+    EXPECT_EQ(x[9], L'A');
+    EXPECT_POISONED(x[10]);
+}
+
 TEST(MemorySanitizer, mbtowc) {
   const char *x = "abc";
   wchar_t wx;