diff --git a/src/config.h.in b/src/config.h.in
index c57cd2f..1099531 100644
--- a/src/config.h.in
+++ b/src/config.h.in
@@ -39,6 +39,9 @@
 /* Defined to the size of an int */
 #undef SIZEOF_INT
 
+/* Defined to the size of time_t */
+#undef SIZEOF_TIME_T
+
 /* Define when wchar_t is only 2 bytes. */
 #undef SMALL_WCHAR_T