diff --git a/lunarsky/__init__.py b/lunarsky/__init__.py
index 9eeef94..35c308e 100644
--- a/lunarsky/__init__.py
+++ b/lunarsky/__init__.py
@@ -1,3 +1,11 @@
+import sys
+
+if sys.platform == "darwin":
+    # On MacOS, need to set multiprocessing to fork by default
+    import multiprocessing
+
+    multiprocessing.set_start_method("fork", force=True)
+
 from .moon import *  # noqa
 from .mcmf import *  # noqa
 from .topo import *  # noqa