diff --git a/include/internal/refcount.h b/include/internal/refcount.h
index 0c07c42..5899e8c 100644
--- a/include/internal/refcount.h
+++ b/include/internal/refcount.h
@@ -9,6 +9,8 @@
 #ifndef OSSL_INTERNAL_REFCOUNT_H
 # define OSSL_INTERNAL_REFCOUNT_H
 
+# include <openssl/e_os2.h>
+
 /* Used to checking reference counts, most while doing perl5 stuff :-) */
 # if defined(OPENSSL_NO_STDIO)
 #  if defined(REF_PRINT)
@@ -30,7 +32,8 @@
 
 typedef _Atomic int CRYPTO_REF_COUNT;
 
-static inline int CRYPTO_UP_REF(_Atomic int *val, int *ret, void *lock)
+static inline int CRYPTO_UP_REF(_Atomic int *val, int *ret,
+                                ossl_unused void *lock)
 {
     *ret = atomic_fetch_add_explicit(val, 1, memory_order_relaxed) + 1;
     return 1;
@@ -46,7 +49,8 @@
  * to mutable members doesn't have to be serialized anymore, which would
  * otherwise imply an acquire fence. Hence conditional acquire fence...
  */
-static inline int CRYPTO_DOWN_REF(_Atomic int *val, int *ret, void *lock)
+static inline int CRYPTO_DOWN_REF(_Atomic int *val, int *ret,
+                                  ossl_unused void *lock)
 {
     *ret = atomic_fetch_sub_explicit(val, 1, memory_order_relaxed) - 1;
     if (*ret == 0)
@@ -60,13 +64,14 @@
 
 typedef int CRYPTO_REF_COUNT;
 
-static __inline__ int CRYPTO_UP_REF(int *val, int *ret, void *lock)
+static __inline__ int CRYPTO_UP_REF(int *val, int *ret, ossl_unused void *lock)
 {
     *ret = __atomic_fetch_add(val, 1, __ATOMIC_RELAXED) + 1;
     return 1;
 }
 
-static __inline__ int CRYPTO_DOWN_REF(int *val, int *ret, void *lock)
+static __inline__ int CRYPTO_DOWN_REF(int *val, int *ret,
+                                      ossl_unused void *lock)
 {
     *ret = __atomic_fetch_sub(val, 1, __ATOMIC_RELAXED) - 1;
     if (*ret == 0)
@@ -77,13 +82,15 @@
 #   define HAVE_ATOMICS 1
 typedef volatile int CRYPTO_REF_COUNT;
 
-static __inline int CRYPTO_UP_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_UP_REF(volatile int *val, int *ret,
+                                  ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd((void *)val, 1) + 1;
     return 1;
 }
 
-static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret,
+                                    ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd((void *)val, -1) - 1;
     return 1;
@@ -101,13 +108,15 @@
 #     define _ARM_BARRIER_ISH _ARM64_BARRIER_ISH
 #    endif
 
-static __inline int CRYPTO_UP_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_UP_REF(volatile int *val, int *ret,
+                                  ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd_nf(val, 1) + 1;
     return 1;
 }
 
-static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret,
+                                    ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd_nf(val, -1) - 1;
     if (*ret == 0)
@@ -127,13 +136,15 @@
 #     endif
 #    endif
 
-static __inline int CRYPTO_UP_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_UP_REF(volatile int *val, int *ret,
+                                  ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd(val, 1) + 1;
     return 1;
 }
 
-static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret, void *lock)
+static __inline int CRYPTO_DOWN_REF(volatile int *val, int *ret,
+                                    ossl_unused void *lock)
 {
     *ret = _InterlockedExchangeAdd(val, -1) - 1;
     return 1;