diff --git a/build-emacs-for-macos b/build-emacs-for-macos
index 978e1e6..c04d6c9 100755
--- a/build-emacs-for-macos
+++ b/build-emacs-for-macos
@@ -570,7 +570,7 @@ class AbstractEmbedder
   end
 
   def lib_dir_name
-    "lib-#{OS.arch}-#{OS.version}"
+    "lib-#{OS.arch}-#{OS.version.to_s.tr('.', '_')}"
   end
 end