diff --git a/src/tag/commandline.cpp b/src/tag/commandline.cpp
index 89b3567..44af616 100644
--- a/src/tag/commandline.cpp
+++ b/src/tag/commandline.cpp
@@ -29,8 +29,8 @@ namespace din {
 		set_options.add_options()
 			//("switch,s", "Help message")
 			//("option,o", po::value<std::string>()->default_value("default_value"), "Help message")
-			//("option2", po::value<int>(), "Help message")
 			("ids", po::value<std::string>(), "Comma-separated list of IDs of files to be tagged")
+			("set,s", po::value<uint32_t>(), "Limit matching to files belonging to the specified set ID")
 		;
 
 		po::options_description positional_options("Positional options");
diff --git a/src/tag/main.cpp b/src/tag/main.cpp
index 25e5b15..ee66a90 100644
--- a/src/tag/main.cpp
+++ b/src/tag/main.cpp
@@ -82,16 +82,26 @@ int main (int parArgc, char* parArgv[]) {
 	const auto master_tags_string = vm["tags"].as<std::string>();
 	const std::vector<boost::string_ref> tags = dinlib::split_tags(master_tags_string);
 
+	din::OwnerSetInfo set_info;
+	if (vm.count("set")) {
+		set_info.is_valid = true;
+		set_info.group_id = vm["set"].as<uint32_t>();
+	}
+	else {
+		set_info.is_valid = false;
+		set_info.group_id = 0;
+	}
+
 	if (id_mode) {
 		auto ids_string = dinlib::split_tags(vm["ids"].as<std::string>());
 		std::vector<uint64_t> ids;
 		ids.reserve(ids_string.size());
 		std::transform(ids_string.begin(), ids_string.end(), std::back_inserter(ids), &lexical_cast<uint64_t, string_ref>);
-		din::tag_files(settings.db, ids, tags);
+		din::tag_files(settings.db, ids, tags, set_info);
 	}
 	else if (glob_mode) {
 		const auto regexes(globs_to_regex_list(vm["globs"].as<std::vector<std::string>>()));
-		din::tag_files(settings.db, regexes, tags);
+		din::tag_files(settings.db, regexes, tags, set_info);
 	}
 	else {
 		assert(false);
diff --git a/src/tag/tag_postgres.cpp b/src/tag/tag_postgres.cpp
index 0969c17..6d46a51 100644
--- a/src/tag/tag_postgres.cpp
+++ b/src/tag/tag_postgres.cpp
@@ -21,31 +21,53 @@
 #include <ciso646>
 
 namespace din {
-	void tag_files (const dinlib::SettingsDB& parDB, const std::vector<uint64_t>& parFiles, const std::vector<boost::string_ref>& parTags) {
+	void tag_files (const dinlib::SettingsDB& parDB, const std::vector<uint64_t>& parFiles, const std::vector<boost::string_ref>& parTags, OwnerSetInfo parSet) {
 		pq::Connection conn(std::string(parDB.username), std::string(parDB.password), std::string(parDB.dbname), std::string(parDB.address), parDB.port);
 		conn.connect();
 
-		const std::string query =
-			"UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"id\"=ANY($2);";
-
-		conn.query(query, parTags, parFiles);
+		if (parSet.is_valid) {
+			const std::string query =
+				"UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"id\"=ANY($2) AND \"group_id\"=$3;";
+			conn.query(query, parTags, parFiles, parSet.group_id);
+		}
+		else {
+			const std::string query =
+				"UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"id\"=ANY($2);";
+			conn.query(query, parTags, parFiles);
+		}
 	}
 
-	void tag_files (const dinlib::SettingsDB& parDB, const std::vector<std::string>& parRegexes, const std::vector<boost::string_ref>& parTags) {
+	void tag_files (const dinlib::SettingsDB& parDB, const std::vector<std::string>& parRegexes, const std::vector<boost::string_ref>& parTags, OwnerSetInfo parSet) {
 		pq::Connection conn(std::string(parDB.username), std::string(parDB.password), std::string(parDB.dbname), std::string(parDB.address), parDB.port);
 		conn.connect();
 
-		if (parRegexes.size() == 1) {
-			const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"path\" ~ $2;";
-			conn.query(query, parTags, parRegexes.front());
+		if (parSet.is_valid) {
+			if (parRegexes.size() == 1) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"group_id\"=$2 AND \"path\" ~ $3;";
+				conn.query(query, parTags, parSet.group_id, parRegexes.front());
+			}
+			else if (parRegexes.size() > 1) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"group_id\"=$2 AND \"path\" ~ ANY($3);";
+				conn.query(query, parTags, parSet.group_id, parRegexes);
+			}
+			else if (parRegexes.size() == 0) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) WHERE \"group_id\"=$2 ORDER BY 1);";
+				conn.query(query, parTags, parSet.group_id);
+			}
 		}
-		else if (parRegexes.size() > 1) {
-			const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"path\" ~ ANY($2);";
-			conn.query(query, parTags, parRegexes);
-		}
-		else if (parRegexes.size() == 0) {
-			const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1);";
-			conn.query(query, parTags);
+		else {
+			if (parRegexes.size() == 1) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"path\" ~ $2;";
+				conn.query(query, parTags, parRegexes.front());
+			}
+			else if (parRegexes.size() > 1) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1) WHERE \"path\" ~ ANY($2);";
+				conn.query(query, parTags, parRegexes);
+			}
+			else if (parRegexes.size() == 0) {
+				const std::string query = "UPDATE \"files\" SET \"tags\" = ARRAY(SELECT DISTINCT UNNEST(\"tags\" || $1) ORDER BY 1);";
+				conn.query(query, parTags);
+			}
 		}
 	}
 } //namespace din
diff --git a/src/tag/tag_postgres.hpp b/src/tag/tag_postgres.hpp
index 3fae186..70e5877 100644
--- a/src/tag/tag_postgres.hpp
+++ b/src/tag/tag_postgres.hpp
@@ -32,8 +32,8 @@ namespace din {
 		bool is_valid;
 	};
 
-	void tag_files ( const dinlib::SettingsDB& parDB, const std::vector<uint64_t>& parFiles, const std::vector<boost::string_ref>& parTags );
-	void tag_files ( const dinlib::SettingsDB& parDB, const std::vector<std::string>& parRegexes, const std::vector<boost::string_ref>& parTags );
+	void tag_files ( const dinlib::SettingsDB& parDB, const std::vector<uint64_t>& parFiles, const std::vector<boost::string_ref>& parTags, OwnerSetInfo parSet );
+	void tag_files ( const dinlib::SettingsDB& parDB, const std::vector<std::string>& parRegexes, const std::vector<boost::string_ref>& parTags, OwnerSetInfo parSet );
 } //namespace din
 
 #endif