diff --git a/src/ledwand_dither.rs b/src/ledwand_dither.rs
index 95ffe02..9f3a634 100644
--- a/src/ledwand_dither.rs
+++ b/src/ledwand_dither.rs
@@ -1,6 +1,7 @@
 //! Based on https://github.com/WarkerAnhaltRanger/CCCB_Ledwand
 
 use image::GrayImage;
+use log::error;
 use servicepoint::{Bitmap, DisplayBitVec, PIXEL_HEIGHT};
 
 type GrayHistogram = [usize; 256];
@@ -217,8 +218,15 @@ fn ostromoukhov_dither_pixel(
     destination.set(position, destination_value);
 
     let mut diffuse = |to: usize, mat: i16| {
-        let diffuse_value = source[to] as i16 + mat;
-        source[to] = diffuse_value.clamp(u8::MIN.into(), u8::MAX.into()) as u8;
+        match source.get(to) {
+            None => {
+                error!("ostromoukhov_dither_pixel - invalid index {to}");
+            }
+            Some(val) => {
+                let diffuse_value = *val as i16 + mat;
+                source[to] = diffuse_value.clamp(u8::MIN.into(), u8::MAX.into()) as u8;
+            }
+        };
     };
 
     let lookup = if destination_value {
diff --git a/src/main.rs b/src/main.rs
index a485526..cdae13c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,7 +7,7 @@ use crate::{
 };
 use clap::Parser;
 use log::debug;
-use servicepoint::{Brightness, HardResetCommand, UdpSocketExt};
+use servicepoint::{Brightness, HardResetCommand};
 
 mod brightness;
 mod cli;