diff --git a/config.mk b/config.mk
index 18a346b..6245c40 100644
--- a/config.mk
+++ b/config.mk
@@ -1,12 +1,12 @@
 MAKEFLAGS="-j $(grep -c ^processor /proc/cpuinfo)"
 
 CXXFLAGS:=$(CXXFLAGS) -std=c++20 -Wall -Wextra -Werror=switch -Werror=return-type -Werror=unused-result -Wno-maybe-uninitialized
-CPPFLAGS:=$(CPPFLAGS) -Ilib/expected/ -Ilib/ut/ -Ilib/midi/include -I. -Ilib/bestline/
+CPPFLAGS:=$(CPPFLAGS) -Ilib/expected/ -Ilib/midi/include -I. -Ilib/bestline/
 
-RELEASE_FLAGS=-O3
+RELEASE_FLAGS=-O2
 DEBUG_FLAGS=-O0 -ggdb -fsanitize=undefined -DDebug
 
 CXX=g++
 
-LDFLAGS=-L./lib/midi/
+LDFLAGS=-L./lib/midi/ -flto
 LDLIBS=-lmidi-alsa -lasound -lpthread -static-libgcc -static-libstdc++
diff --git a/musique/interpreter/builtin_functions.cc b/musique/interpreter/builtin_functions.cc
index 8270883..9a5ec9c 100644
--- a/musique/interpreter/builtin_functions.cc
+++ b/musique/interpreter/builtin_functions.cc
@@ -21,13 +21,13 @@ void Interpreter::register_callbacks()
 
 /// Check if type has index method
 template<typename T>
-concept With_Index_Method = requires (T t, Interpreter interpreter, usize position) {
+concept With_Index_Method = requires (T &t, Interpreter interpreter, usize position) {
 	{ t.index(interpreter, position) } -> std::convertible_to<Result<Value>>;
 };
 
 /// Check if type has either (index operator or method) and size() method
 template<typename T>
-concept Iterable = (With_Index_Method<T> || With_Index_Operator<T>) && requires (T const t) {
+concept Iterable = (With_Index_Method<T> || With_Index_Operator<T>) && requires (T const& t) {
 	{ t.size() } -> std::convertible_to<usize>;
 };
 
@@ -44,7 +44,8 @@ static Result<std::vector<Value>> deep_flat(Interpreter &interpreter, Iterable a
 		}
 
 		if (auto collection = get_if<Collection>(element)) {
-			std::ranges::move(Try(deep_flat(interpreter, *collection)), std::back_inserter(result));
+			auto array = Try(deep_flat(interpreter, *collection));
+			std::move(array.begin(), array.end(), std::back_inserter(result));
 		} else {
 			result.push_back(std::move(element));
 		}
@@ -709,7 +710,7 @@ static Result<Value> builtin_reverse(Interpreter &i, std::vector<Value> args)
 /// Get minimum of arguments
 static Result<Value> builtin_min(Interpreter &i, std::vector<Value> args)
 {
-	auto array = Try(deep_flat(i, std::move(args)));
+	auto array = Try(deep_flat(i, args));
 	if (auto min = std::ranges::min_element(array); min != array.end())
 		return *min;
 	return Value{};
@@ -718,7 +719,7 @@ static Result<Value> builtin_min(Interpreter &i, std::vector<Value> args)
 /// Get maximum of arguments
 static Result<Value> builtin_max(Interpreter &i, std::vector<Value> args)
 {
-	auto array = Try(deep_flat(i, std::move(args)));
+	auto array = Try(deep_flat(i, args));
 	if (auto max = std::ranges::max_element(array); max != array.end())
 		return *max;
 	return Value{};
@@ -741,7 +742,7 @@ static Result<Value> builtin_partition(Interpreter &i, std::vector<Value> args)
 
 	Array tuple[2] = {};
 	for (auto &value : array) {
-		tuple[Try(predicate(i, { std::move(value) })).truthy()].elements.push_back(std::move(value));
+		tuple[Try(predicate(i, { value })).truthy()].elements.push_back(std::move(value));
 	}
 
 	return Array {{
diff --git a/regression-tests/builtin/typeof.mq b/regression-tests/builtin/typeof.mq
new file mode 100644
index 0000000..48f0f03
--- /dev/null
+++ b/regression-tests/builtin/typeof.mq
@@ -0,0 +1,7 @@
+say (typeof (call flat));
+say (typeof 0);
+say (typeof []);
+say (typeof c);
+say (typeof false);
+say (typeof nil);
+say (typeof say);
diff --git a/regression-tests/builtin/uniq.mq b/regression-tests/builtin/uniq.mq
new file mode 100644
index 0000000..3d087fc
--- /dev/null
+++ b/regression-tests/builtin/uniq.mq
@@ -0,0 +1,5 @@
+say (uniq (up 10 & down 10));
+say (uniq [1;1;1;3;5;3;4;4;1]);
+
+-- Multiple uniq applications shouldn't matter
+say (uniq (uniq [1;1;1;3;5;3;4;4;1]));
diff --git a/regression-tests/builtin/unique.mq b/regression-tests/builtin/unique.mq
new file mode 100644
index 0000000..92a808c
--- /dev/null
+++ b/regression-tests/builtin/unique.mq
@@ -0,0 +1,5 @@
+say (unique (up 10 & down 10));
+say (unique [1;1;1;3;5;3;4;4;1]);
+
+-- Multiple unique applications shouldn't matter
+say (unique (unique [1;1;1;3;5;3;4;4;1]));