diff --git a/unac/Makefile.am b/unac/Makefile.am
index 316116e1..45c2631a 100644
--- a/unac/Makefile.am
+++ b/unac/Makefile.am
@@ -20,7 +20,7 @@
 # Documentation
 #
 man_MANS = unaccent.1 unac.3
-INCLUDES = -DUNAC_VERSION=\"$(VERSION)\"
+AM_CPPFLAGS = -DUNAC_VERSION=\"$(VERSION)\"
 
 #
 # Support programs