diff --git a/fastxml/proc.py b/fastxml/proc.py
index 086644c..01b399f 100644
--- a/fastxml/proc.py
+++ b/fastxml/proc.py
@@ -46,8 +46,10 @@ def f2(*args):
 def fork_call(f):
     def f2(*args):
         queue = multiprocessing.Queue(1)
-        p = multiprocessing.Process(target=_remote_call, args=(queue, f, args))
-        p.start()
+        ctx = multiprocessing.get_context('fork')
+        p = ctx.Process(target=_remote_call, args=(queue, f, args))
+        if __name__ == '__main__':
+            p.start()
         return ForkResult(queue, p)
 
     return f2
diff --git a/fastxml/trainer.py b/fastxml/trainer.py
index 90cbc70..25e88d1 100644
--- a/fastxml/trainer.py
+++ b/fastxml/trainer.py
@@ -462,7 +462,8 @@ def f(node):
         return Tree(rootIdx, W_stack, b, t, probs)
 
     def fit(self, X, y, weights=None):
-        self.roots = self._build_roots(X, y, weights)
+        if __name__ == '__main__':
+            self.roots = self._build_roots(X, y, weights)
         if self.leaf_classifiers:
             self.norms_, self.uxs_, self.xr_ = self._compute_leaf_probs(X, y)