diff --git a/CHANGELOG.md b/CHANGELOG.md
index d64d89e..155fbc7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,14 +9,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
-- Printing version number on non-quiet launch, or when provided `--version` or `:version`
 - Builtin function documentation generation from C++ Musique implementation source code
 - New builtins: digits
+- Negative numbers!
 
 ### Removed
 
 - Release builder, since it's separate part of the project
 
+### Fixed
+
+- `ceil`, `round`, `floor` didn't behave well with negative numbers
+- `duration` wasn't filling note length from context and summed all notes inside chord, when it should take max
+- `try` evaluated arguments too quickly
+
 ## [0.3.1]
 
 ### Fixed
diff --git a/doc/musique-vs-languages-cheatsheet.template b/doc/musique-vs-languages-cheatsheet.template
index a8aa2ac..b423933 100644
--- a/doc/musique-vs-languages-cheatsheet.template
+++ b/doc/musique-vs-languages-cheatsheet.template
@@ -74,7 +74,7 @@ r add 1, 3
 
 n Wywołanie funkcji
 n nie przymujących argumentów
-m constant := (say 42, 10);
+m constant := (say 42, 10),
 m say (call foo)
 p def constant():
 p   print(42)
@@ -199,7 +199,7 @@ c w SonicPi nie ma domyślnej długości nuty;
 c za każdym razem trzeba ją definiować
 
 n Zmiana oktawy do 4tej
-m oct 4;
+m oct 4,
 c w SonicPi domyślna oktawa
 c jest ustalona jako 4
 
diff --git a/musique/interpreter/builtin_functions.cc b/musique/interpreter/builtin_functions.cc
index 56c6225..026a9b0 100644
--- a/musique/interpreter/builtin_functions.cc
+++ b/musique/interpreter/builtin_functions.cc
@@ -741,7 +741,7 @@ static Result<Value> builtin_map(Interpreter &interpreter, std::vector<Value> ar
 //:
 //: # Przykład
 //: ```
-//: 
+//:
 //: ```
 /// Scan computes inclusive prefix sum
 static Result<Value> builtin_scan(Interpreter &interpreter, std::vector<Value> args)
@@ -1071,9 +1071,11 @@ static Result<Value> builtin_duration(Interpreter &interpreter, std::vector<Valu
 	auto total = Number{};
 	for (auto &arg : args) {
 		Try(traverse(interpreter, std::move(arg), [&](Chord &c) {
+			auto chord_length = Number();
 			for (Note &note : c.notes) {
-				total += note.length ? *note.length : interpreter.current_context->length;
+				chord_length = std::max(chord_length, note.length ? *note.length : interpreter.current_context->length);
 			}
+			total += chord_length;
 		}));
 	}
 	return total;
@@ -1149,7 +1151,7 @@ static Result<Value> builtin_permute(Interpreter &i, std::vector<Value> args)
 	return array;
 }
 
-//: Funkcja `sortuje` elementy od najmniejszego do największego (w tym nuty). 
+//: Funkcja `sortuje` elementy od najmniejszego do największego (w tym nuty).
 //:
 //: # Sortowanie liczb
 //: ```
diff --git a/musique/lexer/lexer.cc b/musique/lexer/lexer.cc
index be90fc5..b91e322 100644
--- a/musique/lexer/lexer.cc
+++ b/musique/lexer/lexer.cc
@@ -105,7 +105,7 @@ auto Lexer::next_token() -> Result<std::variant<Token, End_Of_File>>
 
 	// Lex numeric literals
 	// They may have following forms: 0, 0.1
-	if (consume_if(unicode::is_digit)) {
+	if (consume_if(unicode::is_digit) || consume_if('-', unicode::is_digit)) {
 		while (consume_if(unicode::is_digit)) {}
 		if (peek() == '.') {
 			consume();
diff --git a/musique/value/number.cc b/musique/value/number.cc
index 5f8d0dd..ed90677 100644
--- a/musique/value/number.cc
+++ b/musique/value/number.cc
@@ -242,7 +242,7 @@ parse_fractional:
 				.location = std::move(token.location)
 			};
 		}
-		result += Number{ frac, pow10(frac_end - num_end) };
+		result += Number{ (result.num < 0 ? -1 : 1) * frac, pow10(frac_end - num_end) };
 	}
 
 	return result.simplify();
diff --git a/regression-tests/builtin/ceil.mq b/regression-tests/builtin/ceil.mq
index 27a78f8..17eceb7 100644
--- a/regression-tests/builtin/ceil.mq
+++ b/regression-tests/builtin/ceil.mq
@@ -1,8 +1,8 @@
-say (ceil (0 - 4)),
-say (ceil (0 - 4.2)),
-say (ceil (0 - 4.5)),
-say (ceil (0 - 4.8)),
-say (ceil (0 - 5)),
+say (ceil -4),
+say (ceil -4.2),
+say (ceil -4.5),
+say (ceil -4.8),
+say (ceil -5),
 
 say (ceil 4),
 say (ceil 4.2),
diff --git a/regression-tests/builtin/duration.mq b/regression-tests/builtin/duration.mq
new file mode 100644
index 0000000..28114de
--- /dev/null
+++ b/regression-tests/builtin/duration.mq
@@ -0,0 +1,5 @@
+len (1/4),
+say (duration (chord c e g)),
+say (duration c),
+say (duration (c hn e hn)),
+say (duration (c 0.3)),
diff --git a/regression-tests/builtin/floor.mq b/regression-tests/builtin/floor.mq
index 0696ec1..f98c9d0 100644
--- a/regression-tests/builtin/floor.mq
+++ b/regression-tests/builtin/floor.mq
@@ -1,8 +1,8 @@
-say (floor (0 - 4)),
-say (floor (0 - 4.2)),
-say (floor (0 - 4.5)),
-say (floor (0 - 4.8)),
-say (floor (0 - 5)),
+say (floor -4),
+say (floor -4.2),
+say (floor -4.5),
+say (floor -4.8),
+say (floor -5),
 
 say (floor 4),
 say (floor 4.2),
diff --git a/regression-tests/builtin/range.mq b/regression-tests/builtin/range.mq
index 61ae424..656ddaf 100644
--- a/regression-tests/builtin/range.mq
+++ b/regression-tests/builtin/range.mq
@@ -1,17 +1,17 @@
 say (range 0),
-say (range (0 - 1)),
+say (range -1),
 say (range 10),
 say (range 1 10),
 say (range 1 10 2),
 
 say (up 0),
-say (up (0 - 1)),
+say (up -1),
 say (up 10),
 say (up 1 10),
 say (up 1 10 2),
 
 say (down 0),
-say (down (0 - 1)),
+say (down -1),
 say (down 10),
 say (down 1 10),
 say (down 1 10 2),
diff --git a/regression-tests/builtin/round.mq b/regression-tests/builtin/round.mq
index 09b9fa9..07eabf4 100644
--- a/regression-tests/builtin/round.mq
+++ b/regression-tests/builtin/round.mq
@@ -1,8 +1,8 @@
-say (round (0 - 4)),
-say (round (0 - 4.2)),
-say (round (0 - 4.5)),
-say (round (0 - 4.8)),
-say (round (0 - 5)),
+say (round -4),
+say (round -4.2),
+say (round -4.5),
+say (round -4.8),
+say (round -5),
 
 say (round 4),
 say (round 4.2),
diff --git a/regression-tests/test_db.json b/regression-tests/test_db.json
index 599f1ab..4ed1bcc 100644
--- a/regression-tests/test_db.json
+++ b/regression-tests/test_db.json
@@ -270,6 +270,18 @@
           "5"
         ],
         "stderr_lines": []
+      },
+      {
+        "name": "duration.mq",
+        "exit_code": 0,
+        "stdin_lines": [],
+        "stdout_lines": [
+          "3/4",
+          "1/4",
+          "1",
+          "3/10"
+        ],
+        "stderr_lines": []
       }
     ]
   }
diff --git a/scripts/test.mk b/scripts/test.mk
index 23df39a..3afa48c 100644
--- a/scripts/test.mk
+++ b/scripts/test.mk
@@ -1,3 +1,3 @@
-test: bin/debug/musique
+test: bin/$(os)/debug/musique
 	python3 scripts/test.py