diff --git a/Installation/CMakeLists.txt b/Installation/CMakeLists.txt
index f16e99d4a1a..cfaff45d430 100644
--- a/Installation/CMakeLists.txt
+++ b/Installation/CMakeLists.txt
@@ -644,8 +644,11 @@ foreach (lib ${CGAL_SUPPORTING_3RD_PARTY_LIBRARIES})
   list( FIND CGAL_ESSENTIAL_3RD_PARTY_LIBRARIES "${lib}" POSITION )
   if ( "${POSITION}" STRGREATER "-1" ) # if lib is essential
    option(WITH_${lib} "Select external library ${lib}" ON)
-  else()
-    option(WITH_${lib} "Select external library ${lib}" OFF)
+  else() #GMPXX set in CGAL_SetupGMP.cmake
+    string(COMPARE EQUAL "${lib}" "GMPXX" IS_LIB_GMPXX)
+    if(NOT ${IS_LIB_GMPXX})
+      option(WITH_${lib} "Select external library ${lib}" OFF)
+    endif()
   endif()
 
 endforeach()
diff --git a/Installation/cmake/modules/CGAL_SetupGMP.cmake b/Installation/cmake/modules/CGAL_SetupGMP.cmake
index 1a8c28a3c13..26fc412e135 100644
--- a/Installation/cmake/modules/CGAL_SetupGMP.cmake
+++ b/Installation/cmake/modules/CGAL_SetupGMP.cmake
@@ -23,12 +23,14 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CGAL_MODULES_DIR})
 
 find_package(GMP REQUIRED)
 find_package(MPFR REQUIRED)
+find_package(GMPXX QUIET)
 
-if(NOT DEFINED WITH_GMPXX)
+if(NOT GMPXX_FOUND)
   option(CGAL_WITH_GMPXX "Use CGAL with GMPXX: use C++ classes of GNU MP instead of CGAL wrappers" OFF)
-endif()
-if(WITH_GMPXX OR CGAL_WITH_GMPXX)
-  find_package(GMPXX REQUIRED)
+  option(WITH_GMPXX "Select external library GMPXX" OFF)
+else()
+  option(CGAL_WITH_GMPXX "Use CGAL with GMPXX: use C++ classes of GNU MP instead of CGAL wrappers" ON)
+  option(WITH_GMPXX "Select external library GMPXX" ON)
 endif()
 
 #.rst: