diff --git a/CMakeLists.txt b/CMakeLists.txt
index a2ade77..3fd20f4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -77,7 +77,9 @@ set(ABSL_DEPS
     absl_synchronization
     )
 
-# If a top-level project has called add_directory(abseil-cpp) already (possibly
+add_subdirectory(abseil-cpp)
+
+# If a top-level project has called add_subdirectory(abseil-cpp) already (possibly
 # indirectly), let that take precedence over any copy of Abseil that might have
 # been installed on the system. And likewise for ICU, GoogleTest and Benchmark.
 if(NOT TARGET absl::base)
