diff --git a/userspace/engine/rule_loader_collector.cpp b/userspace/engine/rule_loader_collector.cpp
index 18103950db2..ee0fdd83953 100644
--- a/userspace/engine/rule_loader_collector.cpp
+++ b/userspace/engine/rule_loader_collector.cpp
@@ -182,10 +182,7 @@ void rule_loader::collector::append(configuration& cfg, macro_info& info) {
 }
 
 void rule_loader::collector::define(configuration& cfg, rule_info& info) {
-	const auto* prev = m_rule_infos.at(info.name);
-	THROW(prev && prev->source != info.source,
-	      "Rule has been re-defined with a different source",
-	      info.ctx);
+	auto prev __attribute__((unused)) = find_prev_rule(info);
 
 	const auto* source = cfg.sources.at(info.source);
 	if(!source) {
@@ -205,7 +202,7 @@ void rule_loader::collector::define(configuration& cfg, rule_info& info) {
 }
 
 void rule_loader::collector::append(configuration& cfg, rule_update_info& info) {
-	auto prev = m_rule_infos.at(info.name);
+	auto prev = find_prev_rule(info);
 
 	THROW(!prev, ERROR_NO_PREVIOUS_RULE_APPEND, info.ctx);
 	THROW(!info.has_any_value(),
@@ -275,7 +272,7 @@ void rule_loader::collector::append(configuration& cfg, rule_update_info& info)
 }
 
 void rule_loader::collector::selective_replace(configuration& cfg, rule_update_info& info) {
-	auto prev = m_rule_infos.at(info.name);
+	auto prev = find_prev_rule(info);
 
 	THROW(!prev, ERROR_NO_PREVIOUS_RULE_REPLACE, info.ctx);
 	THROW(!info.has_any_value(),
@@ -330,6 +327,28 @@ void rule_loader::collector::selective_replace(configuration& cfg, rule_update_i
 	replace_info(prev, info, m_cur_index++);
 }
 
+template<typename ruleInfo>
+rule_loader::rule_info* rule_loader::collector::find_prev_rule(ruleInfo& info) {
+	auto ret = m_rule_infos.at(info.name);
+
+	std::string old_source = (ret ? ret->source : "");
+
+	if(old_source == "") {
+		old_source = falco_common::syscall_source;
+	}
+
+	std::string new_source = info.source;
+	if(new_source == "") {
+		new_source = falco_common::syscall_source;
+	}
+
+	THROW(ret && (old_source != new_source),
+	      "Rule has been re-defined with a different source",
+	      info.ctx);
+
+	return ret;
+}
+
 void rule_loader::collector::enable(configuration& cfg, rule_info& info) {
 	auto prev = m_rule_infos.at(info.name);
 	THROW(!prev, "Rule has 'enabled' key but no rule by that name already exists", info.ctx);
diff --git a/userspace/engine/rule_loader_collector.h b/userspace/engine/rule_loader_collector.h
index 6abf862961c..d995f6c54d0 100644
--- a/userspace/engine/rule_loader_collector.h
+++ b/userspace/engine/rule_loader_collector.h
@@ -97,6 +97,9 @@ class collector {
 	virtual void selective_replace(configuration& cfg, rule_update_info& info);
 
 private:
+	template<typename ruleInfo>
+	rule_info* find_prev_rule(ruleInfo& info);
+
 	uint32_t m_cur_index;
 	indexed_vector<rule_info> m_rule_infos;
 	indexed_vector<macro_info> m_macro_infos;