diff --git a/Polyhedron/demo/Polyhedron/Plugins/Point_set/CMakeLists.txt b/Polyhedron/demo/Polyhedron/Plugins/Point_set/CMakeLists.txt
index 5d96fc86288..12b2e9f9056 100644
--- a/Polyhedron/demo/Polyhedron/Plugins/Point_set/CMakeLists.txt
+++ b/Polyhedron/demo/Polyhedron/Plugins/Point_set/CMakeLists.txt
@@ -12,7 +12,7 @@ if(EIGEN3_FOUND)
   endif()
   find_package(GLPK QUIET)
   if(GLPK_FOUND)
-    include_directories(BEFORE ${GLPK_INCLUDE_DIRS})
+    include_directories(BEFORE ${GLPK_INCLUDE_DIR})
     set(polyfit_linked_libraries ${polyfit_linked_libraries} ${GLPK_LIBRARIES})
     set(polyfit_compile_definitions ${polyfit_compile_definitions} "-DCGAL_USE_GLPK")
   endif()