diff --git a/src/imb.zig b/src/imb.zig
index 0574ae0..92b5a00 100644
--- a/src/imb.zig
+++ b/src/imb.zig
@@ -134,7 +134,7 @@ fn bitsSet(comptime T: type, value: T) u8 {
     return count;
 }
 
-fn findCodeword(character: u13) u13 {
+fn findCodeword(character: u13) ?u13 {
     const b = bitsSet(u13, character);
     if (b == 2) {
         for (character_table_2, 0..) |item, codeword| {
@@ -149,7 +149,8 @@ fn findCodeword(character: u13) u13 {
             }
         }
     }
-    unreachable;
+
+    return null;
 }
 
 fn generateChecksum(data: [13]u8) u16 {
@@ -212,7 +213,7 @@ fn decode(bars: [65]BarType) Error!BarcodeResult {
             else => return error.DecodingError,
         }
 
-        character.* = findCodeword(character.*);
+        character.* = findCodeword(character.*).?;
     }
 
     characters[9] /= 2;
@@ -280,7 +281,6 @@ pub fn decodeString(str: *const [65:0]u8) Error!BarcodeResult {
             else => return error.InvalidCharacter,
         };
     }
-    const thing = try decode(bars);
 
-    return thing;
+    return try decode(bars);
 }
diff --git a/web/imb.wasm b/web/imb.wasm
index c34d468..cba5bfe 100755
Binary files a/web/imb.wasm and b/web/imb.wasm differ
diff --git a/web/index.html b/web/index.html
index ce2e356..d91863e 100644
--- a/web/index.html
+++ b/web/index.html
@@ -13,6 +13,8 @@
 
     <pre id="result"></pre>
 
+    <a href="https://github.com/cjdenio/usps-barcode-decoder">[source]</a>
+
     <script>
       WebAssembly.instantiateStreaming(fetch("imb.wasm")).then(
         ({ instance }) => {