diff --git a/lib/src/utils/index.js b/lib/src/utils/index.js
index d7e64c82..91f254b9 100644
--- a/lib/src/utils/index.js
+++ b/lib/src/utils/index.js
@@ -1,4 +1,9 @@
+const hexRegex = /^[0-9A-Fa-f\sx,]+$/;
+
 export function hexToBytes(hex) {
+  if (!hexRegex.test(hex)) {
+    throw new Error('hex string contains invalid characters');
+  }
   const cleanHex = hex.replaceAll(' ', '').replaceAll('0x', '').replaceAll(',', '');
   const bytes = [];
   for (let c = 0; c < cleanHex.length; c += 2) {