diff --git a/README.md b/README.md
index 8fa1203..ed8ccc4 100644
--- a/README.md
+++ b/README.md
@@ -50,6 +50,7 @@ untiler streamdir [OPTIONS] INPUT_DIR OUTPUT_DIR
 -w, --workers INTEGER        Number of workers in the processing pool
                            [default=4]
 -x, --no-fill                Don't fill in with lower zooms
+-r, --tile-resolution       Size of input tiles for eg 256, 512 etc
 --help                       Show this message and exit.
 ```
 
diff --git a/README.rst b/README.rst
index 70f6c33..6b2a208 100644
--- a/README.rst
+++ b/README.rst
@@ -64,6 +64,7 @@ lower parent "composite" zoom extent
     -w, --workers INTEGER        Number of workers in the processing pool
                                [default=4]
     -x, --no-fill                Don't fill in with lower zooms
+    -r, --tile-resolution       Size of input tiles for eg 256, 512 etc
     --help                       Show this message and exit.
 
 ``streammbtiles``