Index: extern/CMakeLists.txt
--- extern/CMakeLists.txt.orig
+++ extern/CMakeLists.txt
@@ -179,14 +179,7 @@ if(NOT OPENMW_USE_SYSTEM_RECASTNAVIGATION)
     set(RECASTNAVIGATION_TESTS OFF CACHE BOOL "")
     set(RECASTNAVIGATION_EXAMPLES OFF CACHE BOOL "")
 
-    # master on 15 Feb 2021
-    include(FetchContent)
-    FetchContent_Declare(recastnavigation
-        URL https://github.com/recastnavigation/recastnavigation/archive/e75adf86f91eb3082220085e42dda62679f9a3ea.zip
-        URL_HASH SHA512=93a19490cdfa55e98a6af9cc050e94af88fdb95fae2059ceeff28b62f3b48515f5fdd2c806c910550933b6861a4f6a91173ee0ed1b61c1396f7b34d4c78f0793
-        SOURCE_DIR fetched/recastnavigation
-    )
-    FetchContent_MakeAvailableExcludeFromAll(recastnavigation)
+    add_subdirectory("fetched/recastnavigation")
 endif()
 
 if (NOT OPENMW_USE_SYSTEM_SQLITE3)
