--- a/Makefile.am
+++ b/Makefile.am
@@ -105,8 +105,8 @@
 ./src/include/a68g-stddef.h \
 ./src/include/a68g-transput.h \
 ./src/include/a68g-types.h
-includedir = /usr/local/include/algol68g
-include_HEADERS = \
+a68g_includedir = $(pkgincludedir)
+a68g_include_HEADERS = \
 ./a68g-config.h \
 ./src/include/a68g-common.h \
 ./src/include/a68g-compiler.h \
@@ -142,7 +142,7 @@
 ./src/include/a68g-transput.h \
 ./src/include/a68g-types.h
 bin_PROGRAMS = a68g
-a68g_CFLAGS = -DBINDIR='"$(bindir)"' -DINCLUDEDIR='"$(includedir)"'
+a68g_CFLAGS = -DBINDIR='"$(bindir)"' -DINCLUDEDIR='"$(pkgincludedir)"'
 a68g_CPPFLAGS = -I$(top_srcdir)/src/include
 TESTS_ENVIRONMENT=./a68g
 TESTS=\