diff --git a/lib/src/preparation.rs b/lib/src/preparation.rs
index 6435d7c8..bcf08c73 100644
--- a/lib/src/preparation.rs
+++ b/lib/src/preparation.rs
@@ -72,7 +72,7 @@ impl HeaderPrepStrategy for EthHeaderPrepStrategy {
         }
         // Validate extra data
         let extra_data_bytes = block_builder.input.extra_data.len();
-        if extra_data_bytes >= MAX_EXTRA_DATA_BYTES {
+        if extra_data_bytes > MAX_EXTRA_DATA_BYTES {
             bail!(
                 "Invalid extra data: expected <= {}, got {}",
                 MAX_EXTRA_DATA_BYTES,