diff --git a/src/libcharon/plugins/vici/vici_config.c b/src/libcharon/plugins/vici/vici_config.c
index 87d64a77d5..d3039eb186 100644
--- a/src/libcharon/plugins/vici/vici_config.c
+++ b/src/libcharon/plugins/vici/vici_config.c
@@ -55,6 +55,11 @@
 
 #include <stdio.h>
 
+/**
+ *  Maximum proposal length
+ */
+#define MAX_PROPOSAL_LEN   2048
+
 /**
  * Magic value for an undefined lifetime
  */
@@ -594,7 +599,7 @@ static void free_child_data(child_data_t *data)
  */
 static bool parse_proposal(linked_list_t *list, protocol_id_t proto, chunk_t v)
 {
-	char buf[BUF_LEN];
+	char buf[MAX_PROPOSAL_LEN];
 	proposal_t *proposal;
 
 	if (!vici_stringify(v, buf, sizeof(buf)))