diff --git a/hubzilla/addon/cry01/cry01_chain.php b/hubzilla/addon/cry01/cry01_chain.php
index cb070e7..06d37be 100644
--- a/hubzilla/addon/cry01/cry01_chain.php
+++ b/hubzilla/addon/cry01/cry01_chain.php
@@ -414,6 +414,7 @@ function cry01_cache_is_stale() {
 
 function cry01_refresh_balance_cache($g1_pubkey) {
     // Refreshes the balance cache for the given public key.
+    // $g1_pubkey is a 32-byte raw account ID (as returned by cry01_ss58_decode()).
     // The public key comes from the wallet session via the manage POST form — never from config.
     // Returns true on success, false on failure.
     if (!$g1_pubkey) {
@@ -423,9 +424,13 @@ function cry01_refresh_balance_cache($g1_pubkey) {
     $balance = cry01_get_balance($g1_pubkey);
     if ($balance === null) return false;
 
+    // Cache stores the account ID as hex, not raw binary — raw binary bytes
+    // are not valid UTF-8 and cause json_encode() to fail silently (returns
+    // false), which previously resulted in an empty (0-byte) cache file
+    // despite cry01_write_cache() reporting success.
     $cache = cry01_read_cache();
     $cache['balance']      = $balance;
-    $cache['g1_pubkey']    = $g1_pubkey;
+    $cache['g1_pubkey']    = bin2hex($g1_pubkey);
     $cache['refreshed_at'] = date('c');
     return cry01_write_cache($cache);
 }