diff --git a/osbuild.py b/osbuild.py
index 7cf7190e..8b799e91 100644
--- a/osbuild.py
+++ b/osbuild.py
@@ -209,7 +209,8 @@ class Pipeline:
         m.update(json.dumps(pipeline, sort_keys=True).encode())
 
         self.id = m.hexdigest()
-        self.stages = pipeline["stages"]
+        self.base = pipeline.get("base")
+        self.stages = pipeline.get("stages", [])
         self.assembler = pipeline.get("assembler")
         self.objects = objects
 
@@ -220,6 +221,11 @@ class Pipeline:
             "stages": []
         }
         with BuildRoot() as buildroot, tmpfs() as tree:
+            if self.base:
+                input_tree = os.path.join(self.objects, self.base)
+
+                subprocess.run(["cp", "-a", f"{input_tree}/.", tree], check=True)
+
             for i, stage in enumerate(self.stages, start=1):
                 name = stage["name"]
                 options = stage.get("options", {})
diff --git a/samples/base-qcow2.json b/samples/base-qcow2.json
index f328531f..161ed603 100644
--- a/samples/base-qcow2.json
+++ b/samples/base-qcow2.json
@@ -1,13 +1,6 @@
 {
   "name": "base-qcow2",
-  "stages": [
-    {
-      "name": "io.weldr.untree",
-      "options": {
-        "tree": "efc7b094c174d9f5fd66c863db7128415f5df0f073125716f5279554f13a659f"
-      }
-    }
-  ],
+  "base": "f571638c0a21a7141e2391d476433c1679831e4f21df6555c2ef53c4446b7603",
   "assembler":
     {
       "name": "io.weldr.qcow2",
diff --git a/samples/base-targz.json b/samples/base-targz.json
index afddb1ff..52f4a949 100644
--- a/samples/base-targz.json
+++ b/samples/base-targz.json
@@ -1,13 +1,6 @@
 {
   "name": "base-targz",
-  "stages": [
-    {
-      "name": "io.weldr.untree",
-      "options": {
-        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
-      }
-    }
-  ],
+  "base": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
   "assembler": {
     "name": "io.weldr.targz",
     "options": {
diff --git a/samples/base-with-grub2.json b/samples/base-with-grub2.json
index ac3461e4..7a898bc7 100644
--- a/samples/base-with-grub2.json
+++ b/samples/base-with-grub2.json
@@ -1,12 +1,7 @@
 {
   "name": "base-with-grub2",
+  "base": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e",
   "stages": [
-    {
-      "name": "io.weldr.untree",
-      "options": {
-        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
-      }
-    },
     {
       "name": "io.weldr.grub2",
       "systemResourcesFromEtc": ["/etc/grub.d"],
diff --git a/samples/base-with-locale.json b/samples/base-with-locale.json
index b64ba71f..fb1bb261 100644
--- a/samples/base-with-locale.json
+++ b/samples/base-with-locale.json
@@ -1,12 +1,7 @@
 {
   "name": "base-with-locale",
+  "base": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e",
   "stages": [
-    {
-      "name": "io.weldr.untree",
-      "options": {
-        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
-      }
-    },
     {
       "name": "io.weldr.locale",
       "options": {
diff --git a/samples/base-with-selinux.json b/samples/base-with-selinux.json
index 11fcc9ce..f72dcac0 100644
--- a/samples/base-with-selinux.json
+++ b/samples/base-with-selinux.json
@@ -1,12 +1,7 @@
 {
   "name": "base-with-selinux",
+  "base": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e",
   "stages": [
-    {
-      "name": "io.weldr.untree",
-      "options": {
-        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
-      }
-    },
     {
       "name": "io.weldr.selinux",
       "options": {