diff --git a/include/types/action.h b/include/types/action.h
index 570710b..84454e4 100644
--- a/include/types/action.h
+++ b/include/types/action.h
@@ -24,11 +24,6 @@
 
 #include <types/stick_table.h>
 
-struct capture_prm {
-	struct sample_expr *expr;               /* expression used as the key */
-	struct cap_hdr *hdr;                    /* the capture storage */
-};
-
 struct act_rule {
 	struct list list;
 	struct acl_cond *cond;                 /* acl condition to meet */
@@ -62,8 +57,8 @@
 			int action;
 		} http;
 		struct {
-			struct sample_expr *expr;
-			struct cap_hdr *hdr;
+			struct sample_expr *expr; /* expression used as the key */
+			struct cap_hdr *hdr;      /* the capture storage */
 		} cap;
 		struct {
 			struct sample_expr *expr;
@@ -80,10 +75,6 @@
 			void *p[4];
 		} act;                         /* generic pointers to be used by custom actions */
 	} arg;                                 /* arguments used by some actions */
-
-	union {
-		struct capture_prm cap;
-	} act_prm;
 };
 
 #endif /* _TYPES_ACTION_H */
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 8e7830e..cacbccb 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -8226,7 +8226,7 @@
 		if ((curproxy->cap & PR_CAP_FE) && !curproxy->tcp_req.inspect_delay) {
 			list_for_each_entry(trule, &curproxy->tcp_req.inspect_rules, list) {
 				if (trule->action == TCP_ACT_CAPTURE &&
-				    !(trule->act_prm.cap.expr->fetch->val & SMP_VAL_FE_SES_ACC))
+				    !(trule->arg.cap.expr->fetch->val & SMP_VAL_FE_SES_ACC))
 					break;
 				if  ((trule->action >= TCP_ACT_TRK_SC0 && trule->action <= TCP_ACT_TRK_SCMAX) &&
 				     !(trule->arg.trk_ctr.expr->fetch->val & SMP_VAL_FE_SES_ACC))
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index e95ca8c..42f5619 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -1205,11 +1205,11 @@
 			}
 			else if (rule->action == TCP_ACT_CAPTURE) {
 				struct sample *key;
-				struct cap_hdr *h = rule->act_prm.cap.hdr;
+				struct cap_hdr *h = rule->arg.cap.hdr;
 				char **cap = s->req_cap;
 				int len;
 
-				key = sample_fetch_as_type(s->be, sess, s, SMP_OPT_DIR_REQ | partial, rule->act_prm.cap.expr, SMP_T_STR);
+				key = sample_fetch_as_type(s->be, sess, s, SMP_OPT_DIR_REQ | partial, rule->arg.cap.expr, SMP_T_STR);
 				if (!key)
 					continue;
 
@@ -1615,8 +1615,8 @@
 		/* check if we need to allocate an hdr_idx struct for HTTP parsing */
 		curpx->http_needed |= !!(expr->fetch->use & SMP_USE_HTTP_ANY);
 
-		rule->act_prm.cap.expr = expr;
-		rule->act_prm.cap.hdr = hdr;
+		rule->arg.cap.expr = expr;
+		rule->arg.cap.hdr = hdr;
 		rule->action = TCP_ACT_CAPTURE;
 	}
 	else if (strncmp(args[arg], "track-sc", 8) == 0 &&