diff --git a/terracotta/scripts/optimize_rasters.py b/terracotta/scripts/optimize_rasters.py
index 61b21d80..0452ff90 100644
--- a/terracotta/scripts/optimize_rasters.py
+++ b/terracotta/scripts/optimize_rasters.py
@@ -118,6 +118,9 @@ def _named_tempfile(basedir: Union[str, Path]) -> Iterator[str]:
     type=PathlibPath(file_okay=False, writable=True),
     help='Output folder for cloud-optimized rasters. Subdirectories will be flattened.'
 )
+@click.option(
+    '--skip-existing', is_flag=True, default=False, help='Skip existing files'
+)
 @click.option(
     '--overwrite', is_flag=True, default=False, help='Force overwrite of existing files'
 )
@@ -145,6 +148,7 @@ def _named_tempfile(basedir: Union[str, Path]) -> Iterator[str]:
 def optimize_rasters(raster_files: Sequence[Sequence[Path]],
                      output_folder: Path,
                      overwrite: bool = False,
+                     skip_existing: bool = False,
                      resampling_method: str = 'average',
                      reproject: bool = False,
                      in_memory: bool = None,
@@ -214,10 +218,13 @@ def optimize_rasters(raster_files: Sequence[Sequence[Path]],
 
             output_file = output_folder / input_file.with_suffix('.tif').name
 
-            if not overwrite and output_file.is_file():
-                raise click.BadParameter(
-                    f'Output file {output_file!s} exists (use --overwrite to ignore)'
-                )
+            if output_file.is_file():
+                if skip_existing:
+                    continue
+                if not overwrite:
+                    raise click.BadParameter(
+                        f'Output file {output_file!s} exists (use --overwrite or --skip-existing)'
+                    )
 
             with contextlib.ExitStack() as es, warnings.catch_warnings():
                 warnings.filterwarnings('ignore', message='invalid value encountered.*')
diff --git a/tests/scripts/test_optimize_rasters.py b/tests/scripts/test_optimize_rasters.py
index 7eae8ef9..74c16e7d 100644
--- a/tests/scripts/test_optimize_rasters.py
+++ b/tests/scripts/test_optimize_rasters.py
@@ -1,3 +1,4 @@
+import os
 import warnings
 import traceback
 
@@ -149,3 +150,34 @@ def test_optimize_rasters_multiband(tmpdir, unoptimized_raster_file):
         with warnings.catch_warnings():
             warnings.filterwarnings('ignore', 'invalid value encountered.*')
             np.testing.assert_array_equal(src1.read(), src2.read())
+
+
+@pytest.mark.parametrize('extra_flag', ['skip-existing', 'overwrite', None])
+def test_reoptimize(tmpdir, unoptimized_raster_file, extra_flag):
+    from terracotta.scripts import cli
+
+    infile = str(unoptimized_raster_file.dirpath('*.tif'))
+    outfile = tmpdir / 'out.tif'
+
+    # first time
+    runner = CliRunner()
+    args = ['optimize-rasters', infile, '-o', str(outfile)]
+    result = runner.invoke(cli.cli, args)
+    assert result.exit_code == 0
+    ctime = os.stat(outfile).st_ctime
+
+    # second time
+    args = ['optimize-rasters', infile, '-o', str(outfile)]
+    if extra_flag:
+        args.append(f'--{extra_flag}')
+
+    result = runner.invoke(cli.cli, args)
+
+    if extra_flag == 'skip-existing':
+        assert result.exit_code == 0
+        assert os.stat(outfile).st_ctime == ctime
+    elif extra_flag == 'overwrite':
+        assert result.exit_code == 0
+        assert os.stat(outfile).st_ctime != ctime
+    else:
+        assert result.exit_code == 2