--- c_src/Makefile.orig	2021-10-01 21:40:32.270930000 +0200
+++ c_src/Makefile	2021-10-01 21:41:13.958044000 +0200
@@ -86,7 +86,7 @@
     GCC = $(DEF_CC)
 endif
 
-IGL_INCLUDE = -I../_deps/eigen -I../_deps/libigl/include
+IGL_INCLUDE = $(shell pkg-config --cflags eigen3) -I../_deps/libigl/include
 
 # libigl only supports 64bits systems
 ifeq (x"${WORDSIZE}",x"64")