diff --git a/mdbx.h b/mdbx.h
index db7427f6..3ebc59b3 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -921,8 +921,6 @@ LIBMDBX_API int mdbx_env_set_maxdbs(MDB_env *env, MDB_dbi dbs);
 
 /* Get the maximum size of keys and MDB_DUPSORT data we can write.
  *
- * Depends on the compile-time constant MDB_MAXKEYSIZE. Default 511.
- * See MDB_val.
  * [in] env An environment handle returned by mdbx_env_create()
  * Returns The maximum size of a key we can write
  */
diff --git a/src/bits.h b/src/bits.h
index 5537aa5f..45c0d69c 100644
--- a/src/bits.h
+++ b/src/bits.h
@@ -693,7 +693,7 @@ void mdbx_panic(const char *fmt, ...)
 #define mdbx_debug_enabled(type) (1)
 #else
 #define mdbx_debug_enabled(type) (0)
-#endif
+#endif /* NDEBUG */
 #define mdbx_audit_enabled() (0)
 #define mdbx_assert_enabled() (0)
 #endif /* MDB_DEBUG */
diff --git a/src/mdbx.c b/src/mdbx.c
index 977683a2..2f4e17fb 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -317,48 +317,17 @@ txnid_t mdbx_debug_edge;
 /**	The version number for a database's lockfile format. */
 #define MDB_LOCK_VERSION ((MDB_DEVEL) ? 999 : 1)
 
-/**	@brief The max size of a key we can write, or 0 for computed max.
- *
- *	This macro should normally be left alone or set to 0.
- *	Note that a database with big keys or dupsort data cannot be
- *	reliably modified by a liblmdb which uses a smaller max.
- *	The default is 511 for backwards compat, or 0 when #MDB_DEVEL.
- *
- *	Other values are allowed, for backwards compat.  However:
- *	A value bigger than the computed max can break if you do not
- *	know what you are doing, and liblmdb <= 0.9.10 can break when
- *	modifying a DB with keys/dupsort data bigger than its max.
- *
- *	Data items in an #MDB_DUPSORT database are also limited to
- *	this size, since they're actually keys of a sub-DB.  Keys and
- *	#MDB_DUPSORT data items must fit on a node in a regular page.
- */
-#ifndef MDB_MAXKEYSIZE
-#define MDB_MAXKEYSIZE ((MDB_DEVEL) ? 0 : 511)
-#endif
-
-/**	The maximum size of a key we can write to the environment. */
-#if MDB_MAXKEYSIZE
-#define ENV_MAXKEY(env) (MDB_MAXKEYSIZE)
-#else
-#define ENV_MAXKEY(env) ((env)->me_maxkey_limit)
-#endif /* MDB_MAXKEYSIZE */
-
 /**	@brief The maximum size of a data item.
  *
  *	We only store a 32 bit value for node sizes.
  */
 #define MAXDATASIZE 0xffffffffUL
 
-/**	Key size which fits in a #DKBUF.
- *	@ingroup debug
- */
-#define DKBUF_MAXKEYSIZE ((MDB_MAXKEYSIZE) > 0 ? (MDB_MAXKEYSIZE) : 511)
-/**	A key buffer.
- *	@ingroup debug
- *	This is used for printing a hex dump of a key's contents.
- */
-#define DKBUF char kbuf[DKBUF_MAXKEYSIZE * 2 + 1]
+#define DKBUF_MAXKEYSIZE 511 /* FIXME */
+                             /**	Key size which fits in a #DKBUF.
+                              *	@ingroup debug
+                              */
+#define DKBUF char kbuf[DKBUF_MAXKEYSIZE]
 /**	Display a key in hex.
  *	@ingroup debug
  *	Invoke a function to display a key in hex.
@@ -3610,6 +3579,16 @@ fail:
   return rc;
 }
 
+static void __cold mdbx_env_setup_limits(MDB_env *env, size_t pagesize) {
+  env->me_maxfree_1pg = (pagesize - PAGEHDRSZ) / sizeof(pgno_t) - 1;
+  env->me_nodemax =
+      (((pagesize - PAGEHDRSZ) / MDB_MINKEYS) & -2) - sizeof(indx_t);
+  env->me_maxkey_limit = env->me_nodemax - (NODESIZE + sizeof(MDB_db));
+  assert(env->me_maxkey_limit > 42 && env->me_maxkey_limit < pagesize);
+
+  env->me_maxpg = env->me_mapsize / pagesize;
+}
+
 int __cold mdbx_env_create(MDB_env **env) {
   MDB_env *e;
 
@@ -3622,10 +3601,11 @@ int __cold mdbx_env_create(MDB_env **env) {
   e->me_fd = INVALID_HANDLE_VALUE;
   e->me_lfd = INVALID_HANDLE_VALUE;
   e->me_pid = mdbx_getpid();
-  e->me_os_psize = mdbx_syspagesize();
+  mdbx_env_setup_limits(e, e->me_os_psize = mdbx_syspagesize());
   VALGRIND_CREATE_MEMPOOL(e, 0, 0);
   e->me_signature = MDBX_ME_SIGNATURE;
   *env = e;
+
   return MDB_SUCCESS;
 }
 
@@ -3783,8 +3763,7 @@ int __cold mdbx_env_get_maxreaders(MDB_env *env, unsigned *readers) {
   return MDB_SUCCESS;
 }
 
-/** Further setup required for opening an LMDB environment
- */
+/* Further setup required for opening an LMDB environment */
 static int __cold mdbx_env_open2(MDB_env *env, MDB_meta *meta) {
   int newenv = 0;
   int rc = mdbx_env_read_header(env, meta);
@@ -3834,15 +3813,7 @@ static int __cold mdbx_env_open2(MDB_env *env, MDB_meta *meta) {
   if (rc)
     return rc;
 
-  env->me_maxfree_1pg = (env->me_psize - PAGEHDRSZ) / sizeof(pgno_t) - 1;
-  env->me_nodemax =
-      (((env->me_psize - PAGEHDRSZ) / MDB_MINKEYS) & -2) - sizeof(indx_t);
-  env->me_maxkey_limit = env->me_nodemax - (NODESIZE + sizeof(MDB_db));
-  env->me_maxpg = env->me_mapsize / env->me_psize;
-
-  if (MDB_MAXKEYSIZE > env->me_maxkey_limit)
-    return MDB_BAD_VALSIZE;
-
+  mdbx_env_setup_limits(env, env->me_psize);
   return MDB_SUCCESS;
 }
 
@@ -5609,17 +5580,17 @@ int mdbx_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
   if (unlikely(mc->mc_txn->mt_flags & (MDB_TXN_RDONLY | MDB_TXN_BLOCKED)))
     return (mc->mc_txn->mt_flags & MDB_TXN_RDONLY) ? EACCES : MDB_BAD_TXN;
 
-  if (unlikely(key->mv_size > ENV_MAXKEY(env)))
+  if (unlikely(key->mv_size > env->me_maxkey_limit))
     return MDB_BAD_VALSIZE;
 
 #if SIZE_MAX > MAXDATASIZE
   if (unlikely(data->mv_size > ((mc->mc_db->md_flags & MDB_DUPSORT)
-                                    ? ENV_MAXKEY(env)
+                                    ? env->me_maxkey_limit
                                     : MAXDATASIZE)))
     return MDB_BAD_VALSIZE;
 #else
   if ((mc->mc_db->md_flags & MDB_DUPSORT) &&
-      unlikely(data->mv_size > ENV_MAXKEY(env)))
+      unlikely(data->mv_size > env->me_maxkey_limit))
     return MDB_BAD_VALSIZE;
 #endif
 
@@ -9089,9 +9060,9 @@ int mdbx_set_dupsort(MDB_txn *txn, MDB_dbi dbi, MDB_cmp_func *cmp) {
 }
 
 int __cold mdbx_env_get_maxkeysize(MDB_env *env) {
-  if (!env || env->me_signature != MDBX_ME_SIGNATURE)
+  if (!env || env->me_signature != MDBX_ME_SIGNATURE || !env->me_maxkey_limit)
     return EINVAL;
-  return ENV_MAXKEY(env);
+  return env->me_maxkey_limit;
 }
 
 int __cold mdbx_reader_list(MDB_env *env, MDB_msg_func *func, void *ctx) {
diff --git a/src/tools/mdbx_chk.c b/src/tools/mdbx_chk.c
index 1aaaaff2..cc0efdd9 100644
--- a/src/tools/mdbx_chk.c
+++ b/src/tools/mdbx_chk.c
@@ -671,14 +671,6 @@ int main(int argc, char *argv[]) {
     return rc < 0 ? EXIT_FAILURE_MDB : EXIT_FAILURE_SYS;
   }
 
-  rc = mdbx_env_get_maxkeysize(env);
-  if (rc < 0) {
-    error("mdbx_env_get_maxkeysize failed, error %d %s\n", rc,
-          mdbx_strerror(rc));
-    goto bailout;
-  }
-  maxkeysize = rc;
-
   rc = mdbx_env_set_maxdbs(env, MAX_DBI);
   if (rc < 0) {
     error("mdbx_env_set_maxdbs failed, error %d %s\n", rc, mdbx_strerror(rc));
@@ -702,6 +694,14 @@ int main(int argc, char *argv[]) {
     }
   }
 
+  rc = mdbx_env_get_maxkeysize(env);
+  if (rc < 0) {
+    error("mdbx_env_get_maxkeysize failed, error %d %s\n", rc,
+          mdbx_strerror(rc));
+    goto bailout;
+  }
+  maxkeysize = rc;
+
   rc = mdbx_txn_begin(env, NULL, MDB_RDONLY, &txn);
   if (rc) {
     error("mdbx_txn_begin(read-only) failed, error %d %s\n", rc,
@@ -734,11 +734,8 @@ int main(int argc, char *argv[]) {
           sf[i]);
     if (info.me_mapaddr)
       print(" - mapaddr %p\n", info.me_mapaddr);
-    print(" - pagesize %u, max keysize %zu (%s), max readers %u\n",
-          stat.ms_psize, maxkeysize,
-          (maxkeysize == 511) ? "default" : (maxkeysize == 0) ? "devel"
-                                                              : "custom",
-          info.me_maxreaders);
+    print(" - pagesize %u, max keysize %zu, max readers %u\n", stat.ms_psize,
+          maxkeysize, info.me_maxreaders);
     print(" - transactions: last %zu, bottom %zu, lag reading %zi\n",
           info.me_last_txnid, info.me_tail_txnid,
           info.me_last_txnid - info.me_tail_txnid);