diff --git a/CMakeLists.txt b/CMakeLists.txt
index 26e39f0e..d830dd88 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -145,7 +145,7 @@ if(JSRUNTIMEHOST_POLYFILL_XMLHTTPREQUEST)
     set_property(TARGET UrlLib PROPERTY FOLDER Dependencies)
 endif()
 
-if(JSRUNTIMEHOST_POLYFILL_FILE)
+if(JSRUNTIMEHOST_POLYFILL_FILE AND NOT TARGET base-n)
     FetchContent_MakeAvailable_With_Message(base-n)
     add_library(base-n INTERFACE)
     target_include_directories(base-n INTERFACE "${base-n_SOURCE_DIR}/include")