diff --git a/osxphotos/__main__.py b/osxphotos/__main__.py
index 0681487c..85aee599 100644
--- a/osxphotos/__main__.py
+++ b/osxphotos/__main__.py
@@ -1330,13 +1330,32 @@ def export(
         return
 
     # open export database and assign copy/link/unlink functions
+    export_db_path = os.path.join(dest, OSXPHOTOS_EXPORT_DB)
+
+    # check that export isn't in the parent or child of a previously exported library
+    other_db_files = find_files_in_branch(dest, OSXPHOTOS_EXPORT_DB)
+    if other_db_files:
+        click.echo(
+            "WARNING: found other export database files in this destination directory branch.  "
+            + "This likely means you are attempting to export files into a directory "
+            + "that is either the parent or a child directory of a previous export. "
+            + "Proceeding may cause your exported files to be overwritten.",
+            err=True,
+        )
+        click.echo(
+            f"You are exporting to {dest}, found {OSXPHOTOS_EXPORT_DB} files in:"
+        )
+        for other_db in other_db_files:
+            click.echo(f"{other_db}")
+        click.confirm("Do you want to continue?", abort=True)
+
     if dry_run:
-        export_db = ExportDBInMemory(os.path.join(dest, OSXPHOTOS_EXPORT_DB))
+        export_db = ExportDBInMemory(export_db_path)
         # echo = functools.partial(click.echo, err=True)
         # fileutil = FileUtilNoOp(verbose=echo)
         fileutil = FileUtilNoOp
     else:
-        export_db = ExportDB(os.path.join(dest, OSXPHOTOS_EXPORT_DB))
+        export_db = ExportDB(export_db_path)
         fileutil = FileUtil
 
     photos = _query(
@@ -1504,7 +1523,7 @@ def export(
         else:
             photo_str = "photos" if len(results_exported) != 1 else "photo"
             click.echo(f"Exported: {len(results_exported)} {photo_str}")
-        click.echo(f"Elapsed time: {stop_time-start_time} seconds")
+        click.echo(f"Elapsed time: {(stop_time-start_time):.3f} seconds")
     else:
         click.echo("Did not find any photos to export")
 
@@ -2186,7 +2205,7 @@ def get_dirnames_from_template(photo, directory, export_by_date, dest, dry_run):
             dest_path = os.path.join(dest, dirname)
             if not is_valid_filepath(dest_path, platform="auto"):
                 raise ValueError(f"Invalid file path: '{dest_path}'")
-            if not (dry_run or os.path.isdir(dest_path)):
+            if not dry_run and not os.path.isdir(dest_path):
                 os.makedirs(dest_path)
             dest_paths.append(dest_path)
     else:
@@ -2194,5 +2213,42 @@ def get_dirnames_from_template(photo, directory, export_by_date, dest, dry_run):
     return dest_paths
 
 
+def find_files_in_branch(pathname, filename):
+    """ Search a directory branch to find file(s) named filename
+        The branch searched includes all folders below pathname and 
+        the parent tree of pathname but not pathname itself.
+
+        e.g. find filename in children folders and parent folders
+
+    Args:
+        pathname: str, full path of directory to search
+        filename: str, filename to search for
+    
+    Returns: list of full paths to any matching files
+    """
+
+    pathname = pathlib.Path(pathname).resolve()
+    files = []
+
+    # walk down the tree
+    for root, directories, filenames in os.walk(pathname):
+        # for directory in directories:
+        # print(os.path.join(root, directory))
+        for fname in filenames:
+            if fname == filename and pathlib.Path(root) != pathname:
+                files.append(os.path.join(root, fname))
+
+    # walk up the tree
+    path = pathlib.Path(pathname)
+    for root in path.parents:
+        filenames = os.listdir(root)
+        for fname in filenames:
+            filepath = os.path.join(root, fname)
+            if fname == filename and os.path.isfile(filepath):
+                files.append(os.path.join(root, fname))
+
+    return files
+
+
 if __name__ == "__main__":
     cli()  # pylint: disable=no-value-for-parameter
diff --git a/osxphotos/_version.py b/osxphotos/_version.py
index 6cc31831..c194f9d5 100644
--- a/osxphotos/_version.py
+++ b/osxphotos/_version.py
@@ -1,3 +1,3 @@
 """ version info """
 
-__version__ = "0.29.20"
+__version__ = "0.29.21"
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 52f54329..e14a2537 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -1738,6 +1738,59 @@ def test_export_update_basic():
         )
 
 
+def test_export_update_child_folder():
+    """ test export then update into a child folder of previous export """
+    import glob
+    import os
+    import os.path
+
+    import osxphotos
+    from osxphotos.__main__ import export, OSXPHOTOS_EXPORT_DB
+
+    runner = CliRunner()
+    cwd = os.getcwd()
+    # pylint: disable=not-context-manager
+    with runner.isolated_filesystem():
+        # basic export
+        result = runner.invoke(export, [os.path.join(cwd, CLI_PHOTOS_DB), ".", "-V"])
+        assert result.exit_code == 0
+
+        os.mkdir("foo")
+
+        # update into foo
+        result = runner.invoke(
+            export, [os.path.join(cwd, CLI_PHOTOS_DB), "foo", "--update"], input="N\n"
+        )
+        assert result.exit_code != 0
+        assert "WARNING: found other export database files" in result.output
+
+
+def test_export_update_parent_folder():
+    """ test export then update into a parent folder of previous export """
+    import glob
+    import os
+    import os.path
+
+    import osxphotos
+    from osxphotos.__main__ import export, OSXPHOTOS_EXPORT_DB
+
+    runner = CliRunner()
+    cwd = os.getcwd()
+    # pylint: disable=not-context-manager
+    with runner.isolated_filesystem():
+        # basic export
+        os.mkdir("foo")
+        result = runner.invoke(export, [os.path.join(cwd, CLI_PHOTOS_DB), "foo", "-V"])
+        assert result.exit_code == 0
+
+        # update into "."
+        result = runner.invoke(
+            export, [os.path.join(cwd, CLI_PHOTOS_DB), ".", "--update"], input="N\n"
+        )
+        assert result.exit_code != 0
+        assert "WARNING: found other export database files" in result.output
+
+
 @pytest.mark.skipif(exiftool is None, reason="exiftool not installed")
 def test_export_update_exiftool():
     """ test export then update with exiftool """