diff --git a/time_t/GNUmakefile b/time_t/GNUmakefile
index f291b00..cb1e1b7 100644
--- a/time_t/GNUmakefile
+++ b/time_t/GNUmakefile
@@ -1,3 +1,4 @@
+include GNUmakevars
 include GNUmakerules
 
 all: time_t