diff --git a/src/core.c b/src/core.c
index 4eb57d6f..e32e9ba8 100644
--- a/src/core.c
+++ b/src/core.c
@@ -14486,9 +14486,11 @@ __cold int mdbx_env_turn_for_recovery(MDBX_env *env, unsigned target) {
 __cold int mdbx_env_open_for_recovery(MDBX_env *env, const char *pathname,
                                       unsigned target_meta, bool writeable) {
 #if defined(_WIN32) || defined(_WIN64)
-  const wchar_t *pathnameW = nullptr;
+  wchar_t *pathnameW = nullptr;
   OSAL_MB2WIDE(pathname, pathnameW);
-  return mdbx_env_open_for_recoveryW(env, pathnameW, target_meta, writeable);
+  int rc = mdbx_env_open_for_recoveryW(env, pathnameW, target_meta, writeable);
+  osal_free(pathnameW);
+  return rc;
 }
 
 __cold int mdbx_env_open_for_recoveryW(MDBX_env *env, const wchar_t *pathname,
@@ -14675,9 +14677,11 @@ __cold static int handle_env_pathname(MDBX_handle_env_pathname *ctx,
 
 __cold int mdbx_env_delete(const char *pathname, MDBX_env_delete_mode_t mode) {
 #if defined(_WIN32) || defined(_WIN64)
-  const wchar_t *pathnameW = nullptr;
+  wchar_t *pathnameW = nullptr;
   OSAL_MB2WIDE(pathname, pathnameW);
-  return mdbx_env_deleteW(pathnameW, mode);
+  int rc = mdbx_env_deleteW(pathnameW, mode);
+  osal_free(pathnameW);
+  return rc;
 }
 
 __cold int mdbx_env_deleteW(const wchar_t *pathname,
@@ -14766,9 +14770,11 @@ __cold int mdbx_env_deleteW(const wchar_t *pathname,
 __cold int mdbx_env_open(MDBX_env *env, const char *pathname,
                          MDBX_env_flags_t flags, mdbx_mode_t mode) {
 #if defined(_WIN32) || defined(_WIN64)
-  const wchar_t *pathnameW = nullptr;
+  wchar_t *pathnameW = nullptr;
   OSAL_MB2WIDE(pathname, pathnameW);
-  return mdbx_env_openW(env, pathnameW, flags, mode);
+  int rc = mdbx_env_openW(env, pathnameW, flags, mode);
+  osal_free(pathnameW);
+  return rc;
 }
 
 __cold int mdbx_env_openW(MDBX_env *env, const wchar_t *pathname,
@@ -21772,9 +21778,11 @@ __cold int mdbx_env_copy2fd(MDBX_env *env, mdbx_filehandle_t fd,
 __cold int mdbx_env_copy(MDBX_env *env, const char *dest_path,
                          MDBX_copy_flags_t flags) {
 #if defined(_WIN32) || defined(_WIN64)
-  const wchar_t *dest_pathW = nullptr;
+  wchar_t *dest_pathW = nullptr;
   OSAL_MB2WIDE(dest_path, dest_pathW);
-  return mdbx_env_copyW(env, dest_pathW, flags);
+  int rc = mdbx_env_copyW(env, dest_pathW, flags);
+  osal_free(dest_pathW);
+  return rc;
 }
 
 LIBMDBX_API int mdbx_env_copyW(MDBX_env *env, const wchar_t *dest_path,
diff --git a/src/osal.h b/src/osal.h
index 02447376..a8e50a20 100644
--- a/src/osal.h
+++ b/src/osal.h
@@ -765,12 +765,16 @@ MDBX_INTERNAL_FUNC size_t osal_mb2w(wchar_t *dst, size_t dst_n, const char *src,
     const char *const from_tmp = (FROM);                                       \
     const size_t from_mblen = strlen(from_tmp);                                \
     const size_t to_wlen = osal_mb2w(nullptr, 0, from_tmp, from_mblen);        \
-    if (to_wlen < 1 || to_wlen > /* MAX_PATH */ INT16_MAX)                     \
+    if (unlikely(to_wlen < 1 || to_wlen > /* MAX_PATH */ INT16_MAX))           \
       return ERROR_INVALID_NAME;                                               \
-    wchar_t *const to_tmp = _alloca((to_wlen + 1) * sizeof(wchar_t));          \
-    if (to_wlen + 1 !=                                                         \
-        osal_mb2w(to_tmp, to_wlen + 1, from_tmp, from_mblen + 1))              \
+    wchar_t *const to_tmp = osal_malloc((to_wlen + 1) * sizeof(wchar_t));      \
+    if (unlikely(!to_tmp))                                                     \
+      return MDBX_ENOMEM;                                                      \
+    if (unlikely(to_wlen + 1 !=                                                \
+                 osal_mb2w(to_tmp, to_wlen + 1, from_tmp, from_mblen + 1))) {  \
+      osal_free(to_tmp);                                                       \
       return ERROR_INVALID_NAME;                                               \
+    }                                                                          \
     (TO) = to_tmp;                                                             \
   } while (0)