diff --git a/transport.h b/transport.h
index 8ebaaf2..9c10a44 100644
--- a/transport.h
+++ b/transport.h
@@ -13,6 +13,7 @@
 	unsigned self_contained_and_connected : 1;
 	unsigned update_shallow : 1;
 	int depth;
+	const char *deepen_since;
 	const char *uploadpack;
 	const char *receivepack;
 	struct push_cas_option *cas;
@@ -171,6 +172,9 @@
 /* Limit the depth of the fetch if not null */
 #define TRANS_OPT_DEPTH "depth"
 
+/* Limit the depth of the fetch based on time if not null */
+#define TRANS_OPT_DEEPEN_SINCE "deepen-since"
+
 /* Aggressively fetch annotated tags if possible */
 #define TRANS_OPT_FOLLOWTAGS "followtags"