diff --git a/mingw-w64-crt/lib-common/msvcrt.def.in b/mingw-w64-crt/lib-common/msvcrt.def.in
index 5c31c79..26680b8 100644
--- a/mingw-w64-crt/lib-common/msvcrt.def.in
+++ b/mingw-w64-crt/lib-common/msvcrt.def.in
@@ -1928,7 +1928,10 @@
 ; i386 strtoll, strtoull, strtoimax, strtoumax, wcstoll, wcstoull, wcstoimax and wcstoumax aliases provided by emu
 #define WITH_STRTO64_ALIAS
 #endif
-#if defined(__arm__) || defined(__aarch64__)
+#if defined(__arm__) || defined(__aarch64__) || defined(__arm64ec__)
+; This uses functions that are available since Vista. ARM/AArch64/ARM64EC
+; can assume that those fucntions always are available; on x86 we provide
+; fallbacks in the import library.
 #define USE_WCSTOK_S_FOR_WCSTOK
 #define WITH_FSEEKO64_ALIAS
 #endif