diff --git a/parser/signal.cc b/parser/signal.cc
index 5e3eff701..fde038525 100644
--- a/parser/signal.cc
+++ b/parser/signal.cc
@@ -230,6 +230,35 @@ int signal_rule::expand_variables(void)
 	return expand_entry_variables(&peer_label);
 }
 
+static int cmp_set_int(Signals const &lhs, Signals const &rhs)
+{
+	int res = lhs.size() - rhs.size();
+	if (res)
+		return res;
+
+	for (Signals::iterator i = lhs.begin(),
+			       j = rhs.begin();
+	     i != lhs.end(); i++, j++) {
+		res = *i - *j;
+		if (res)
+			return res;
+	}
+
+	return 0;
+}
+
+int signal_rule::cmp(rule_t const &rhs) const
+{
+	int res = perms_rule_t::cmp(rhs);
+	if (res)
+		return res;
+	signal_rule const &trhs = rule_cast<signal_rule const &>(rhs);
+	res = null_strcmp(peer_label, trhs.peer_label);
+	if (res)
+		return res;
+	return cmp_set_int(signals, trhs.signals);
+}
+
 void signal_rule::warn_once(const char *name)
 {
 	rule_t::warn_once(name, "signal rules not enforced");
diff --git a/parser/signal.h b/parser/signal.h
index 391c8b34d..e5df3d2a7 100644
--- a/parser/signal.h
+++ b/parser/signal.h
@@ -57,6 +57,9 @@ public:
 	virtual int expand_variables(void);
 	virtual int gen_policy_re(Profile &prof);
 
+	virtual bool is_mergeable(void) { return true; }
+	virtual int cmp(rule_t const &rhs) const;
+
 protected:
 	virtual void warn_once(const char *name) override;
 };