diff --git a/osbuild/util/ostree.py b/osbuild/util/ostree.py
index 875d9b90..88e0501c 100644
--- a/osbuild/util/ostree.py
+++ b/osbuild/util/ostree.py
@@ -125,3 +125,17 @@ def rev_parse(repo: PathLike, ref: str) -> str:
         raise RuntimeError(msg)
 
     return msg
+
+
+def deployment_path(root: PathLike, osname: str, ref: str, serial: int):
+    """Return the path to a deployment given the parameters"""
+
+    base = os.path.join(root, "ostree")
+
+    repo = os.path.join(base, "repo")
+    stateroot = os.path.join(base, "deploy", osname)
+
+    commit = rev_parse(repo, ref)
+    sysroot = f"{stateroot}/deploy/{commit}.{serial}"
+
+    return sysroot