diff --git a/include/rpc/xdr.h b/include/rpc/xdr.h
index ecf10e1659e..4c75bcc5bbf 100644
--- a/include/rpc/xdr.h
+++ b/include/rpc/xdr.h
@@ -129,14 +129,7 @@ typedef struct XDR {
  * to be decoded.  If this pointer is 0, then the type routines should
  * allocate dynamic storage of the appropriate size and return it.
  */
-#ifdef _KERNEL
-typedef	bool_t (*xdrproc_t)(XDR *, void *, u_int);
-#else
-/*
- * XXX can't actually prototype it, because some take three args!!!
- */
-typedef	bool_t (*xdrproc_t)(XDR *, ...);
-#endif
+typedef	bool_t (*xdrproc_t)(XDR *, void *);
 
 /*
  * Operations defined on a XDR handle
diff --git a/lib/libc/rpc/rpc.3 b/lib/libc/rpc/rpc.3
index 12d19df117a..7ae3ec5c5ae 100644
--- a/lib/libc/rpc/rpc.3
+++ b/lib/libc/rpc/rpc.3
@@ -254,9 +254,9 @@ enum xdr_op {
  * structure of the data type to be decoded.  If this points to 0,
  * then the type routines should allocate dynamic storage of the
  * appropriate size and return it.
- * bool_t  (*xdrproc_t)(XDR *, caddr_t *);
+ * bool_t  (*xdrproc_t)(XDR *, void *);
  */
-typedef  bool_t (*xdrproc_t)();
+typedef  bool_t (*xdrproc_t)(XDR *, void *);
 
 /*
  * The XDR handle.
diff --git a/sys/contrib/openzfs/module/nvpair/nvpair.c b/sys/contrib/openzfs/module/nvpair/nvpair.c
index eb8c14b4a78..cb3a024ec95 100644
--- a/sys/contrib/openzfs/module/nvpair/nvpair.c
+++ b/sys/contrib/openzfs/module/nvpair/nvpair.c
@@ -3246,7 +3246,8 @@ nvs_xdr_nvl_fini(nvstream_t *nvs)
  * xdrproc_t-compatible callbacks for xdr_array()
  */
 
-#if defined(_KERNEL) && defined(__linux__) /* Linux kernel */
+#if (defined(__FreeBSD_version) && __FreeBSD_version >= 1600010) || \
+    defined(_KERNEL) && defined(__linux__) /* Linux kernel */
 
 #define	NVS_BUILD_XDRPROC_T(type)		\
 static bool_t					\
diff --git a/sys/rpc/xdr.h b/sys/rpc/xdr.h
index 4307b510147..b3eafcb864b 100644
--- a/sys/rpc/xdr.h
+++ b/sys/rpc/xdr.h
@@ -133,14 +133,7 @@ typedef struct XDR {
  * to be decoded.  If this pointer is 0, then the type routines should
  * allocate dynamic storage of the appropriate size and return it.
  */
-#ifdef _KERNEL
-typedef	bool_t (*xdrproc_t)(XDR *, void *, ...);
-#else
-/*
- * XXX can't actually prototype it, because some take three args!!!
- */
-typedef	bool_t (*xdrproc_t)(XDR *, ...);
-#endif
+typedef	bool_t (*xdrproc_t)(XDR *, void *);
 
 /*
  * Operations defined on a XDR handle
diff --git a/sys/sys/param.h b/sys/sys/param.h
index a5dd31519ea..410d18b53df 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -74,7 +74,7 @@
  * cannot include sys/param.h and should only be updated here.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1600009
+#define __FreeBSD_version 1600010
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,