diff --git a/atdna/atdnaHelpers.cmake b/atdna/atdnaHelpers.cmake
index 861b63f..f80c317 100644
--- a/atdna/atdnaHelpers.cmake
+++ b/atdna/atdnaHelpers.cmake
@@ -3,8 +3,8 @@
 # across all dependencies.
 #
 
-# CMake 3.20: Transform add_custom_command DEPFILE for Ninja
-cmake_policy(SET CMP0116 NEW)
+# CMake 3.20: Don't transform add_custom_command DEPFILE for Ninja
+cmake_policy(SET CMP0116 OLD)
 
 function(_atdna_gather_include_directories_impl target_name)
   get_target_property(target_dependencies ${target_name} INTERFACE_LINK_LIBRARIES)