diff --git a/src/vars.c b/src/vars.c
index 6fc58dd33..30bcf3df9 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -529,6 +529,7 @@ int vars_check_arg(struct arg *arg, char **err)
 {
 	char *name;
 	enum vars_scope scope;
+	struct sample empty_smp = { };
 
 	/* Check arg type. */
 	if (arg->type != ARGT_STR) {
@@ -543,6 +544,9 @@ int vars_check_arg(struct arg *arg, char **err)
 	if (!name)
 		return 0;
 
+	if (scope == SCOPE_PROC && !var_set(name, scope, &empty_smp, VF_CREATEONLY|VF_PERMANENT))
+		return 0;
+
 	/* properly destroy the chunk */
 	chunk_destroy(&arg->data.str);
 
@@ -823,6 +827,7 @@ static enum act_parse_ret parse_store(const char **args, int *arg, struct proxy
 	int var_len;
 	const char *kw_name;
 	int flags, set_var = 0; /* 0=unset-var, 1=set-var, 2=set-var-fmt */
+	struct sample empty_smp = { };
 
 	if (strncmp(var_name, "set-var-fmt", 11) == 0) {
 		var_name += 11;
@@ -856,6 +861,10 @@ static enum act_parse_ret parse_store(const char **args, int *arg, struct proxy
 	if (!rule->arg.vars.name)
 		return ACT_RET_PRS_ERR;
 
+	if (rule->arg.vars.scope == SCOPE_PROC &&
+	    !var_set(rule->arg.vars.name, rule->arg.vars.scope, &empty_smp, VF_CREATEONLY|VF_PERMANENT))
+		return 0;
+
 	/* There is no fetch method when variable is unset. Just set the right
 	 * action and return. */
 	if (!set_var) {