diff --git a/src/db/CapacitorChannel.php b/src/db/CapacitorChannel.php
index 8bf81f6..d7846c6 100644
--- a/src/db/CapacitorChannel.php
+++ b/src/db/CapacitorChannel.php
@@ -143,46 +143,47 @@ class CapacitorChannel {
     return array_key_exists("modified_", $rowValues);
   }
 
-  final function serialize($item): string {
-    return serialize($item);
+  final function serialize($item): ?string {
+    return $item !== null? serialize($item): null;
   }
 
-  final function unserialize(string $string) {
-    return unserialize($string);
+  final function unserialize(?string $serial) {
+    return $serial !== null? unserialize($serial): null;
   }
 
   const SUM_DEFINITION = "varchar(40)";
 
-  final function sum(?string $string): string {
-    return sha1($string);
+  final function sum(?string $serial, $value=null): ?string {
+    if ($serial === null) $serial = $this->serialize($value);
+    return $serial !== null? sha1($serial): null;
   }
 
-  final function isSerialKey(string &$key): bool {
+  final function isSerialCol(string &$key): bool {
     return str::del_suffix($key, "__");
   }
 
-  final function getSumKeys(string $key): array {
+  final function getSumCols(string $key): array {
     return ["${key}__", "${key}__sum_"];
   }
 
   function getSum(string $key, $value): array {
-    $keys = $this->getSumKeys($key);
-    if ($value !== null) $value = $this->serialize($value);
-    $sum = $this->sum($value);
-    return array_combine($keys, [$value, $sum]);
+    $sumCols = $this->getSumCols($key);
+    $serial = $this->serialize($value);
+    $sum = $this->sum($serial, $value);
+    return array_combine($sumCols, [$serial, $sum]);
   }
 
   function wasSumModified(string $key, $value, array $prowValues): bool {
-    $sumKey = $this->getSumKeys($key)[1];
-    $sum = $this->getSum($key, $value)[$sumKey];
-    $psum = $prowValues[$sumKey] ?? sha1(serialize($prowValues[$key] ?? null));
+    $sumCol = $this->getSumCols($key)[1];
+    $sum = $this->sum(null, $value);
+    $psum = $prowValues[$sumCol] ?? $this->sum(null, $prowValues[$key] ?? null);
     return $sum !== $psum;
   }
 
   function _wasSumModified(string $key, array $row, array $prow): bool {
-    $sumKey = $this->getSumKeys($key)[1];
-    $sum = $row[$sumKey] ?? null;
-    $psum = $prow[$sumKey] ?? null;
+    $sumCol = $this->getSumCols($key)[1];
+    $sum = $row[$sumCol] ?? null;
+    $psum = $prow[$sumCol] ?? null;
     return $sum !== $psum;
   }
 
diff --git a/src/db/CapacitorStorage.php b/src/db/CapacitorStorage.php
index 88d6465..276a1b5 100644
--- a/src/db/CapacitorStorage.php
+++ b/src/db/CapacitorStorage.php
@@ -58,9 +58,14 @@ abstract class CapacitorStorage {
       $key = $col;
       if ($key === $index) {
         $index++;
-      } elseif ($channel->isSerialKey($key)) {
+      } elseif ($channel->isSerialCol($key)) {
+        [$serialCol, $sumCol] = $channel->getSumCols($key);
         if (array_key_exists($key, $values)) {
-          A::merge($row, $channel->getSum($key, $values[$key]));
+          $sum = $channel->getSum($key, $values[$key]);
+          $row[$serialCol] = $sum[$serialCol];
+          if (array_key_exists($sumCol, $cols)) {
+            $row[$sumCol] = $sum[$sumCol];
+          }
         }
       } else {
         if (array_key_exists($key, $values)) {
@@ -82,7 +87,7 @@ abstract class CapacitorStorage {
       if ($key === $index) {
         $index++;
       } elseif (!array_key_exists($col, $row)) {
-      } elseif ($channel->isSerialKey($key)) {
+      } elseif ($channel->isSerialCol($key)) {
         $value = $row[$col];
         if ($value !== null) $value = $channel->unserialize($value);
         $values[$key] = $value;