diff --git a/include/haproxy/stick_table-t.h b/include/haproxy/stick_table-t.h
index 33c719cbc..fe23848dd 100644
--- a/include/haproxy/stick_table-t.h
+++ b/include/haproxy/stick_table-t.h
@@ -119,7 +119,7 @@ union stktable_data {
 	unsigned long long std_t_ull;
 	struct freq_ctr std_t_frqp;
 	struct dict_entry *std_t_dict;
-};
+} __attribute__((packed));
 
 /* known data types */
 struct stktable_data_type {