diff --git a/lib/fog/proxmox/helpers/disk_helper.rb b/lib/fog/proxmox/helpers/disk_helper.rb
index c18814b..1a6434e 100644
--- a/lib/fog/proxmox/helpers/disk_helper.rb
+++ b/lib/fog/proxmox/helpers/disk_helper.rb
@@ -136,7 +136,7 @@ def self.to_int_gb(size_bytes)
 
       def self.extract_size(disk_value)
         size = extract_option('size', disk_value)
-        size = to_int_gb(to_bytes(size)).to_s if size.match?(/\d+(G)/)
+        size = to_int_gb(to_bytes(size)).to_s if size&.match?(/\d+(G)/)
         size
       end
 
diff --git a/spec/helpers/disk_helper_spec.rb b/spec/helpers/disk_helper_spec.rb
index a320d2a..16fa5d9 100644
--- a/spec/helpers/disk_helper_spec.rb
+++ b/spec/helpers/disk_helper_spec.rb
@@ -30,7 +30,7 @@
   end
 
   let(:scsi) do
-    { scsi0: 'local-lvm:vm-100-disk-1,size=8,cache=none' }
+    { scsi0: 'local-lvm:vm-100-disk-1,size=8,cache=none', scsi1: 'zdata:vm-221-disk-0' }
   end
 
   let(:virtio1) do
@@ -118,6 +118,13 @@
       assert_equal('8', size)
     end
 
+    it 'returns scsi get zdata storage and volid with no size' do
+      storage, volid, size = Fog::Proxmox::DiskHelper.extract_storage_volid_size(scsi[:scsi1])
+      assert_equal('zdata', storage)
+      assert_equal('zdata:vm-221-disk-0', volid)
+      assert_nil size
+    end
+
     it 'returns virtio get local storage volid and size' do
       storage, volid, size = Fog::Proxmox::DiskHelper.extract_storage_volid_size(virtio[:virtio1])
       assert_equal('local', storage)