diff --git a/src/test/gtest/CMakeLists.txt b/src/test/gtest/CMakeLists.txt
index 4e1bbcd652e9581df326a7ad484e9f98a2aa5650..5ff6db603357a6e6751fe632135f937b389e240f 100644
--- a/src/test/gtest/CMakeLists.txt
+++ b/src/test/gtest/CMakeLists.txt
@@ -31,7 +31,7 @@ ExternalProject_Add(googletest
     PREFIX "${CMAKE_CURRENT_BINARY_DIR}"
     # Disable install step
     INSTALL_COMMAND ""
-    UPDATE_DISCONNECTED 1
+    UPDATE_DISCONNECTED 1 # 1: do not update googletest; 0: update googletest via github
 )
 
 # Get GTest source and binary directories from CMake project