diff --git a/core/lls_core/models/lattice_data.py b/core/lls_core/models/lattice_data.py
index d001a229..699ebb59 100644
--- a/core/lls_core/models/lattice_data.py
+++ b/core/lls_core/models/lattice_data.py
@@ -89,18 +89,27 @@ def parse_workflow(cls, v: Any):
 
     @validator("crop")
     def default_z_range(cls, v: CropParams, values: dict):
-        # If any part of the z range is missing, assume the user wants all Z indices
         if v is None:
             return v
         with ignore_keyerror():
+            # Fill in missing parts of the z range with the min/max z values
             default_start = 0
             default_end = values["input_image"].sizes["Z"]
+
+            # Set defaults
             if v.z_range is None:
                 v.z_range = (default_start, default_end)
             if v.z_range[0] is None:
                 v.z_range[0] = default_start
             if v.z_range[1] is None:
                 v.z_range[1] = default_end
+
+            # Validate
+            if v.z_range[1] > default_end:
+                raise ValueError(f"The z-index endpoint of {v.z_range[1]} is outside the size of the z-axis ({default_end})")
+            if v.z_range[0] < default_start:
+                raise ValueError(f"The z-index start of {v.z_range[0]} is outside the size of the z-axis")
+
             return v
 
     @validator("time_range", pre=True, always=True)
diff --git a/plugin/napari_lattice/fields.py b/plugin/napari_lattice/fields.py
index 30164378..12707de8 100644
--- a/plugin/napari_lattice/fields.py
+++ b/plugin/napari_lattice/fields.py
@@ -397,7 +397,6 @@ class CroppingFields(NapariFieldGroup):
         value = (0, 1),
         options = dict(
             min = 0,
-            max = 1
         ),
     )
     errors = field(Label).with_options(label="Errors")