diff --git a/src/Makefile.am b/src/Makefile.am
index 15caf2c..06676d0 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -3,7 +3,7 @@ SUBDIRS = redshift-gtk
 
 # I18n
 localedir = $(datadir)/locale
-INCLUDES = -DLOCALEDIR=\"$(localedir)\"
+AM_CPPFLAGS = -DLOCALEDIR=\"$(localedir)\"
 
 # redshift Program
 bin_PROGRAMS = redshift