Index: extern/CMakeLists.txt
--- extern/CMakeLists.txt.orig
+++ extern/CMakeLists.txt
@@ -178,11 +178,13 @@ if(NOT OPENMW_USE_SYSTEM_RECASTNAVIGATION)
     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 MD5=af905d121ef9d1cdfa979b0495cba059
-        SOURCE_DIR fetched/recastnavigation
-    )
-    FetchContent_MakeAvailableExcludeFromAll(recastnavigation)
+#    include(FetchContent)
+#    FetchContent_Declare(recastnavigation
+#        URL https://github.com/recastnavigation/recastnavigation/archive/e75adf86f91eb3082220085e42dda62679f9a3ea.zip
+#        URL_HASH MD5=af905d121ef9d1cdfa979b0495cba059
+#        SOURCE_DIR fetched/recastnavigation
+#    )
+#    FetchContent_MakeAvailableExcludeFromAll(recastnavigation)
+
+    add_subdirectory("fetched/recastnavigation")
 endif()