diff --git a/Installation/lib/cmake/CGAL/CGALConfig.cmake b/Installation/lib/cmake/CGAL/CGALConfig.cmake
index ad259f4c753..73624767ee1 100644
--- a/Installation/lib/cmake/CGAL/CGALConfig.cmake
+++ b/Installation/lib/cmake/CGAL/CGALConfig.cmake
@@ -22,7 +22,7 @@ set( CGAL_REQUESTED_COMPONENTS ${CGAL_FIND_COMPONENTS} )
 set(CGAL_CURRENT_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 function(_detect_branch_build VAR_NAME)
-  if(IS_DIRECTORY ${CGAL_CONFIG_DIR}/../../../../Installation)
+  if(IS_DIRECTORY ${CGAL_CONFIG_DIR}/../../../../Installation/package_info/Installation/)
     set(${VAR_NAME} TRUE PARENT_SCOPE)
   else()
     set(${VAR_NAME} FALSE PARENT_SCOPE)
@@ -34,6 +34,7 @@ if(BRANCH_BUILD)
   set(CGAL_ROOT ${CGAL_CONFIG_DIR}/../../../..)
   set(CGAL_INSTALLATION_PACKAGE_DIR ${CGAL_ROOT}/Installation)
   set(CGAL_GRAPHICSVIEW_PACKAGE_DIR ${CGAL_ROOT}/GraphicsView)
+  set(CGAL_MODULES_DIR ${CGAL_ROOT}/Installation/cmake/modules)
   file(GLOB packages_dirs ${CGAL_ROOT}/*)
 #  message("packages_dirs: ${packages_dirs}")
   foreach(package_dir ${packages_dirs})
@@ -47,6 +48,15 @@ if(BRANCH_BUILD)
     endif()
   endforeach()
 else()
+  # not BRANCH_BUILD: it can be an installed CGAL, or the tarball layout
+  if(EXISTS ${CGAL_CONFIG_DIR}/CGAL_add_test.cmake)
+    # installed CGAL
+    set(CGAL_MODULES_DIR ${CGAL_CONFIG_DIR})
+  else()
+    # tarball
+    set(CGAL_MODULES_DIR ${CGAL_ROOT}/cmake/modules)
+  endif()
+
   set(CGAL_ROOT ${CGAL_CONFIG_DIR}/../../..)
   set(CGAL_INSTALLATION_PACKAGE_DIR ${CGAL_ROOT})
   set(CGAL_GRAPHICSVIEW_PACKAGE_DIR ${CGAL_ROOT})
@@ -60,7 +70,6 @@ if(NOT CGAL_FOUND)
   return()
 endif()
 
-set(CGAL_MODULES_DIR ${CGAL_CONFIG_DIR}/../../../cmake/modules)
 list(APPEND CMAKE_MODULE_PATH ${CGAL_MODULES_DIR})
 
 include( ${CGAL_MODULES_DIR}/CGAL_SCM.cmake )