diff --git a/protect/control/v1/common.proto b/protect/control/v1/common.proto
index 7d5db29..8f1d5e1 100644
--- a/protect/control/v1/common.proto
+++ b/protect/control/v1/common.proto
@@ -482,6 +482,7 @@ message ZoneScratchDiskSpec {
   oneof backend {
     ZoneScratchDiskSpecImage image = 1;
     ZoneScratchDiskSpecStaticBlock block = 2;
+    ZoneScratchDiskInternalTmpfs internal_tmpfs = 3;
   }
 }
 
@@ -494,6 +495,13 @@ message ZoneScratchDiskSpecStaticBlock {
   string device = 2;
 }
 
+message ZoneScratchDiskInternalTmpfs {
+  oneof size {
+    uint32 percent = 1;
+    uint64 exact = 2;
+  }
+}
+
 message ZoneDeviceStatus {
   repeated ZoneDiskStatus disks = 1;
   ZoneMountStatus mount = 2;