diff --git a/src/http_act.c b/src/http_act.c
index 1c7a1d4..2eac125 100644
--- a/src/http_act.c
+++ b/src/http_act.c
@@ -723,7 +723,10 @@
 	if (rule->action_ptr != http_action_res_capture_by_id)
 		return 1;
 
-	if (rule->arg.capid.idx >= px->nb_rsp_cap) {
+	/* capture slots can only be declared in frontends, so we can't check their
+	 * existence in backends at configuration parsing step
+	 */
+	if (px->cap & PR_CAP_FE && rule->arg.capid.idx >= px->nb_rsp_cap) {
 		memprintf(err, "unable to find capture id '%d' referenced by http-response capture rule",
 			  rule->arg.capid.idx);
 		return 0;