diff --git a/src/robofish/io/file.py b/src/robofish/io/file.py
index 5115ed8fc057fb3b1302ccbc23ca78913fce7ee6..86a580e2963c8f1c5141105ab422fa38dbf55287 100644
--- a/src/robofish/io/file.py
+++ b/src/robofish/io/file.py
@@ -65,7 +65,7 @@ class File(h5py.File):
         path: Union[str, Path] = None,
         mode: str = "r",
         *,  # PEP 3102
-        world_size_cm: List[int] = None,
+        world_size_cm: List[float] = None,
         validate: bool = False,
         validate_when_saving: bool = True,
         strict_validate: bool = False,
@@ -94,7 +94,7 @@ class File(h5py.File):
             'w'        Create file, truncate if exists
             'x'        Create file, fail if exists
             'a'        Read/write if exists, create otherwise
-        world_size_cm : [int, int] , optional
+        world_size_cm : [float, float] , optional
             side lengths [x, y] of the world in cm.
             rectangular world shape is assumed.
         validate: bool, default=False