diff --git a/nhf/build.py b/nhf/build.py
index 4d4c6c2..3e6ece3 100644
--- a/nhf/build.py
+++ b/nhf/build.py
@@ -214,7 +214,7 @@ class Submodel:
     def write_to(self, obj, path: str):
         x = self._method(obj)
         assert isinstance(x, Model), f"Unexpected type: {type(x)}"
-        x.build_all(path)
+        x.build_all(path, prefix=False)
 
     @classmethod
     def methods(cls, subject):
@@ -271,11 +271,17 @@ class Model:
             total += 1
         return total
 
-    def build_all(self, output_dir: Union[Path, str] = "build", verbose=1):
+    def build_all(
+            self,
+            output_dir: Union[Path, str] = "build",
+            prefix: bool = True,
+            verbose=1):
         """
         Build all targets in this model and write the results to file
         """
         output_dir = Path(output_dir)
+        if prefix:
+            output_dir = output_dir / self.name
         targets = Target.methods(self)
         for t in targets.values():
             file_name = t.file_name