diff --git a/CMakeLists.txt b/CMakeLists.txt
index 66462bfe96e..c7f9ace726f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -46,9 +46,10 @@ option(
 
 message("== CMake setup (DONE) ==\n")
 
-# Enable testing with CGAL_ENABLE_TESTING. Historically, users would enable the tests
-# by specifying BUILD_TESTING so if CGAL_ENABLE_TESTING is not enabled, we will set it
-# to the value of BUILD_TESTING
+# Enable testing with CGAL_ENABLE_TESTING. Before CGAL-6.0, users would enable
+# the tests by specifying BUILD_TESTING. For compatibility, If BUILD_TESTING is
+# set, that is the default value for CGAL_ENABLE_TESTING. Otherwise, the default
+# value is OFF.
 option(CGAL_ENABLE_TESTING "Build the testing tree." ${BUILD_TESTING})
 if(CGAL_ENABLE_TESTING AND NOT POLICY CMP0064)
   message(
diff --git a/Installation/CMakeLists.txt b/Installation/CMakeLists.txt
index 5fea17ecb9a..6f49a308bd1 100644
--- a/Installation/CMakeLists.txt
+++ b/Installation/CMakeLists.txt
@@ -105,8 +105,11 @@ else(CGAL_BRANCH_BUILD)
       "${CGAL_SOURCE_DIR}"
       CACHE INTERNAL "Directory containing the GraphicsView package")
 
-  # Enable testing with CGAL_ENABLE_TESTING
-  option(CGAL_ENABLE_TESTING "Build the testing tree." OFF)
+# Enable testing with CGAL_ENABLE_TESTING. Before CGAL-6.0, users would enable
+# the tests by specifying BUILD_TESTING. For compatibility, If BUILD_TESTING is
+# set, that is the default value for CGAL_ENABLE_TESTING. Otherwise, the default
+# value is OFF.
+option(CGAL_ENABLE_TESTING "Build the testing tree." ${BUILD_TESTING})
   if(CGAL_ENABLE_TESTING)
     enable_testing()
   endif()
diff --git a/Installation/cmake/modules/CGAL_add_test.cmake b/Installation/cmake/modules/CGAL_add_test.cmake
index 1f2d35ade0c..8304207ec83 100644
--- a/Installation/cmake/modules/CGAL_add_test.cmake
+++ b/Installation/cmake/modules/CGAL_add_test.cmake
@@ -3,7 +3,11 @@ if(CGAL_add_test_included)
 endif(CGAL_add_test_included)
 set(CGAL_add_test_included TRUE)
 
-option(CGAL_ENABLE_TESTING "Build the testing tree." OFF)
+# Enable testing with CGAL_ENABLE_TESTING. Before CGAL-6.0, users would enable
+# the tests by specifying BUILD_TESTING. For compatibility, If BUILD_TESTING is
+# set, that is the default value for CGAL_ENABLE_TESTING. Otherwise, the default
+# value is OFF.
+option(CGAL_ENABLE_TESTING "Build the testing tree." ${BUILD_TESTING})
 
 if(CGAL_ENABLE_TESTING)
   enable_testing()