diff --git a/CMakeLists.txt b/CMakeLists.txt
index 16bfb9a..b51922a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -15,7 +15,7 @@
   ${CMAKE_MODULE_PATH}
   )
 
-if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR OR LIBUNWIND_STANDALONE_BUILD)
   project(libunwind)
 
   # Rely on llvm-config.