diff --git a/src/proto_http.c b/src/proto_http.c
index a5323e4..2622e2b 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -8682,10 +8682,13 @@
 	}
 	if (-occ > found)
 		return 0;
+
 	/* OK now we have the last occurrence in [hist_ptr-1], and we need to
-	 * find occurrence -occ, so we have to check [hist_ptr+occ].
+	 * find occurrence -occ. 0 <= hist_ptr < MAX_HDR_HISTORY, and we have
+	 * -10 <= occ <= -1. So we have to check [hist_ptr%MAX_HDR_HISTORY+occ]
+	 * to remain in the 0..9 range.
 	 */
-	hist_ptr += occ;
+	hist_ptr += occ + MAX_HDR_HISTORY;
 	if (hist_ptr >= MAX_HDR_HISTORY)
 		hist_ptr -= MAX_HDR_HISTORY;
 	*vptr = ptr_hist[hist_ptr];