diff --git a/include/proto/stick_table.h b/include/proto/stick_table.h
index 38ec9ae..7381737 100644
--- a/include/proto/stick_table.h
+++ b/include/proto/stick_table.h
@@ -23,6 +23,7 @@
 #ifndef _PROTO_STICK_TABLE_H
 #define _PROTO_STICK_TABLE_H
 
+#include <common/errors.h>
 #include <types/stick_table.h>
 
 #define stktable_data_size(type) (sizeof(((union stktable_data*)0)->type))
@@ -48,21 +49,27 @@
 int stktable_get_data_type(char *name);
 struct proxy *find_stktable(const char *name);
 
-/* reserve some space for data type <type>. Return non-0 if OK, or 0 if already
- * allocated (or impossible type).
+/* reserve some space for data type <type>, and associate argument at <sa> if
+ * not NULL. Returns PE_NONE (0) if OK or an error code among :
+ *   - PE_ENUM_OOR if <type> does not exist
+ *   - PE_EXIST if <type> is already registered
  */
-static inline int stktable_alloc_data_type(struct stktable *t, int type)
+static inline int stktable_alloc_data_type(struct stktable *t, int type, const char *sa)
 {
 	if (type >= STKTABLE_DATA_TYPES)
-		return 0;
+		return PE_ENUM_OOR;
 
 	if (t->data_ofs[type])
 		/* already allocated */
-		return 0;
+		return PE_EXIST;
 
 	t->data_size      += stktable_data_types[type].data_length;
 	t->data_ofs[type]  = -t->data_size;
-	return 1;
+	/* right now only int type is supported, but we may later support type-
+	 * specific arg type.
+	 */
+	t->data_arg[type].i = sa ? atoi(sa) : 0;
+	return PE_NONE;
 }
 
 /* return pointer for data type <type> in sticky session <ts> of table <t>, or
diff --git a/include/types/stick_table.h b/include/types/stick_table.h
index 4cd18d3..caca0be 100644
--- a/include/types/stick_table.h
+++ b/include/types/stick_table.h
@@ -50,6 +50,13 @@
 	STKTABLE_DATA_TYPES       /* Number of data types, must always be last */
 };
 
+/* The types of optional arguments to stored data */
+enum {
+	ARG_T_NONE = 0,           /* data type takes no argument (default) */
+	ARG_T_INT,                /* signed integer */
+	ARG_T_DELAY,              /* a delay which supports time units */
+};
+
 /* stick_table extra data. This is mainly used for casting or size computation */
 union stktable_data {
 	int server_id;
@@ -64,6 +71,7 @@
 struct stktable_data_type {
 	const char *name; /* name of the data type */
 	int data_length;  /* length of this type, or 0 if variable (eg: string) */
+	int arg_type;     /* type of optional argument, ARG_T_* */
 };
 
 /* stick table key type flags */
@@ -104,6 +112,11 @@
 	int expire;               /* time to live for sticky sessions (milliseconds) */
 	int data_size;            /* the size of the data that is prepended *before* stksess */
 	int data_ofs[STKTABLE_DATA_TYPES]; /* negative offsets of present data types, or 0 if absent */
+	union {
+		int i;
+		unsigned int u;
+		void *p;
+	} data_arg[STKTABLE_DATA_TYPES]; /* optional argument of each data type */
 };
 
 struct stktable_data_type stktable_data_types[STKTABLE_DATA_TYPES];