diff --git a/include/internal/refcount.h b/include/internal/refcount.h
index f74f79415d..eddf12415f 100644
--- a/include/internal/refcount.h
+++ b/include/internal/refcount.h
@@ -106,7 +106,7 @@ static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
 #     if _WIN32_WCE >= 0x600
        extern long __cdecl _InterlockedExchangeAdd(long volatile*, long);
 #     else
-       // under Windows CE we still have old-style Interlocked* functions
+       /* under Windows CE we still have old-style Interlocked* functions */
        extern long __cdecl InterlockedExchangeAdd(long volatile*, long);
 #      define _InterlockedExchangeAdd InterlockedExchangeAdd
 #     endif