--- src/lp_solve/Makefile	2023-11-28 23:09:35
+++ src/lp_solve/Makefile	2023-12-07 12:05:43
@@ -1,4 +1,4 @@
-LP_SOLVE_CPPFLAGS=$(CPPFLAGS) -I../../inst/include \
+LP_SOLVE_CPPFLAGS=-I../../inst/include \
                   -I$(R_INCLUDE_DIR) \
                   -DYY_NO_INPUT \
                   -DR_EMBEDDED_LPSOLVE \