diff --git a/library/Vspheredb/Monitoring/Rule/Definition/DiskUsageRuleDefinition.php b/library/Vspheredb/Monitoring/Rule/Definition/DiskUsageRuleDefinition.php
index 77e9ad22..1c5530f3 100644
--- a/library/Vspheredb/Monitoring/Rule/Definition/DiskUsageRuleDefinition.php
+++ b/library/Vspheredb/Monitoring/Rule/Definition/DiskUsageRuleDefinition.php
@@ -37,6 +37,9 @@ public function getInternalDefaults(): array
 
     protected function checkDisk($disk, Settings $settings): ?SingleCheckResult
     {
+        if ((int) $disk->capacity === 0) {
+            return null;
+        }
         if ($filter = $settings->get('disk_path_filter')) {
             if (!$this->filterMatchesPath($filter, $disk->disk_path)) {
                 return null;
diff --git a/library/Vspheredb/Web/Table/VmDiskUsageTable.php b/library/Vspheredb/Web/Table/VmDiskUsageTable.php
index 993a24d2..7936545d 100644
--- a/library/Vspheredb/Web/Table/VmDiskUsageTable.php
+++ b/library/Vspheredb/Web/Table/VmDiskUsageTable.php
@@ -77,7 +77,9 @@ public function renderRow($row)
         }
 
         $free = Format::bytes($row->free_space)
-            . sprintf(' (%0.3f%%)', ($row->free_space / $row->capacity) * 100);
+            . ($row->capacity > 0
+                ? sprintf(' (%0.3f%%)', ($row->free_space / $row->capacity) * 100)
+                : ' (n/a)');
 
         $tr = $this::tr([
             $this::td($caption, [
diff --git a/library/Vspheredb/Web/Widget/SimpleUsageBar.php b/library/Vspheredb/Web/Widget/SimpleUsageBar.php
index eb6e46ce..942c0689 100644
--- a/library/Vspheredb/Web/Widget/SimpleUsageBar.php
+++ b/library/Vspheredb/Web/Widget/SimpleUsageBar.php
@@ -33,7 +33,9 @@ public function __construct($used, $total, $title)
 
     protected function assemble()
     {
-        $usedPercent = $this->used / $this->total;
+        $usedPercent = ($this->total > 0)
+            ? $this->used / $this->total
+            : 0;
 
         $bar = Html::tag('span', [
             'href' => '#',