diff --git a/read.c b/read.c
index 8effa7bf..4a997b96 100644
--- a/read.c
+++ b/read.c
@@ -79,6 +79,7 @@ static struct conditionals *conditionals = &toplevel_conditionals;
 
 static char *default_include_directories[] =
   {
+    INCLUDEDIR,
     "/usr/gnu/include",
     "/usr/local/include",
     "/usr/include",