diff --git a/README.md b/README.md
index 896928cf..52fc7e8a 100644
--- a/README.md
+++ b/README.md
@@ -224,7 +224,7 @@ the user's point of view.
   > due to its internal limitations and unimplemented functions, i.e. the `MDBX_UNABLE_EXTEND_MAPSIZE` error will be returned.
 
 4. Automatic continuous zero-overhead database compactification.
-  > During each commit _libmdbx_ merges suitable freeing pages into unallocated area
+  > During each commit _libmdbx_ merges a freeing pages which adjacent with the unallocated area
   > at the end of file, and then truncates unused space when a lot enough of.
 
 5. The same database format for 32- and 64-bit builds.
diff --git a/src/core.c b/src/core.c
index 72b727a5..ce403ac4 100644
--- a/src/core.c
+++ b/src/core.c
@@ -21175,7 +21175,7 @@ __cold int mdbx_env_set_option(MDBX_env *env, const MDBX_option_t option,
   case MDBX_opt_txn_dp_initial:
     if (unlikely(value > MDBX_PGL_LIMIT || value < CURSOR_STACK * 4))
       return MDBX_EINVAL;
-    if (unlikely(env->me_txn0 == NULL))
+    if (unlikely(env->me_flags & MDBX_RDONLY))
       return MDBX_EACCESS;
     if (lock_needed) {
       err = mdbx_txn_lock(env, false);