diff --git a/src/build/arch/x64/Negate.go b/src/build/arch/x64/Negate.go
new file mode 100644
index 0000000..00ae530
--- /dev/null
+++ b/src/build/arch/x64/Negate.go
@@ -0,0 +1,8 @@
+package x64
+
+import "git.akyoto.dev/cli/q/src/build/cpu"
+
+// NegateRegister negates the value in the register.
+func NegateRegister(code []byte, register cpu.Register) []byte {
+	return encode(code, AddressDirect, 0b011, register, 8, 0xF7)
+}
diff --git a/src/build/arch/x64/Negate_test.go b/src/build/arch/x64/Negate_test.go
new file mode 100644
index 0000000..dd64518
--- /dev/null
+++ b/src/build/arch/x64/Negate_test.go
@@ -0,0 +1,39 @@
+package x64_test
+
+import (
+	"testing"
+
+	"git.akyoto.dev/cli/q/src/build/arch/x64"
+	"git.akyoto.dev/cli/q/src/build/cpu"
+	"git.akyoto.dev/go/assert"
+)
+
+func TestNegateRegister(t *testing.T) {
+	usagePatterns := []struct {
+		Register cpu.Register
+		Code     []byte
+	}{
+		{x64.RAX, []byte{0x48, 0xF7, 0xD8}},
+		{x64.RCX, []byte{0x48, 0xF7, 0xD9}},
+		{x64.RDX, []byte{0x48, 0xF7, 0xDA}},
+		{x64.RBX, []byte{0x48, 0xF7, 0xDB}},
+		{x64.RSP, []byte{0x48, 0xF7, 0xDC}},
+		{x64.RBP, []byte{0x48, 0xF7, 0xDD}},
+		{x64.RSI, []byte{0x48, 0xF7, 0xDE}},
+		{x64.RDI, []byte{0x48, 0xF7, 0xDF}},
+		{x64.R8, []byte{0x49, 0xF7, 0xD8}},
+		{x64.R9, []byte{0x49, 0xF7, 0xD9}},
+		{x64.R10, []byte{0x49, 0xF7, 0xDA}},
+		{x64.R11, []byte{0x49, 0xF7, 0xDB}},
+		{x64.R12, []byte{0x49, 0xF7, 0xDC}},
+		{x64.R13, []byte{0x49, 0xF7, 0xDD}},
+		{x64.R14, []byte{0x49, 0xF7, 0xDE}},
+		{x64.R15, []byte{0x49, 0xF7, 0xDF}},
+	}
+
+	for _, pattern := range usagePatterns {
+		t.Logf("neg %s", pattern.Register)
+		code := x64.NegateRegister(nil, pattern.Register)
+		assert.DeepEqual(t, code, pattern.Code)
+	}
+}
diff --git a/src/build/asm/Finalize.go b/src/build/asm/Finalize.go
index 5c3397d..e38a83f 100644
--- a/src/build/asm/Finalize.go
+++ b/src/build/asm/Finalize.go
@@ -165,6 +165,12 @@ func (a Assembler) Finalize() ([]byte, []byte) {
 				})
 			}
 
+		case NEGATE:
+			switch operands := x.Data.(type) {
+			case *Register:
+				code = x64.NegateRegister(code, operands.Register)
+			}
+
 		case OR:
 			switch operands := x.Data.(type) {
 			case *RegisterNumber:
diff --git a/src/build/asm/Mnemonic.go b/src/build/asm/Mnemonic.go
index 78070f8..e8c778b 100644
--- a/src/build/asm/Mnemonic.go
+++ b/src/build/asm/Mnemonic.go
@@ -4,12 +4,31 @@ type Mnemonic uint8
 
 const (
 	NONE Mnemonic = iota
+
+	// Arithmetic
 	ADD
-	AND
-	CALL
-	COMMENT
-	COMPARE
 	DIV
+	MODULO
+	MUL
+	NEGATE
+	SUB
+
+	// Bitwise operations
+	AND
+	OR
+	SHIFTL
+	SHIFTRS
+	XOR
+
+	// Data movement
+	MOVE
+	LOAD
+	POP
+	PUSH
+	STORE
+
+	// Control flow
+	CALL
 	JE
 	JNE
 	JG
@@ -17,21 +36,13 @@ const (
 	JL
 	JLE
 	JUMP
-	MUL
 	LABEL
-	LOAD
-	MODULO
-	MOVE
-	OR
-	POP
-	PUSH
 	RETURN
-	SHIFTL
-	SHIFTRS
-	STORE
-	SUB
 	SYSCALL
-	XOR
+
+	// Others
+	COMMENT
+	COMPARE
 )
 
 // String returns a human readable version.
@@ -73,6 +84,8 @@ func (m Mnemonic) String() string {
 		return "move"
 	case MUL:
 		return "mul"
+	case NEGATE:
+		return "negate"
 	case OR:
 		return "or"
 	case POP:
diff --git a/src/build/core/ExecuteRegister.go b/src/build/core/ExecuteRegister.go
new file mode 100644
index 0000000..6627acf
--- /dev/null
+++ b/src/build/core/ExecuteRegister.go
@@ -0,0 +1,21 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/build/asm"
+	"git.akyoto.dev/cli/q/src/build/cpu"
+	"git.akyoto.dev/cli/q/src/build/errors"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// ExecuteRegister performs an operation on a single register.
+func (f *Function) ExecuteRegister(operation token.Token, register cpu.Register) error {
+	switch operation.Kind {
+	case token.Negate:
+		f.Register(asm.NEGATE, register)
+
+	default:
+		return errors.New(&errors.InvalidOperator{Operator: operation.Text(f.File.Bytes)}, f.File, operation.Position)
+	}
+
+	return nil
+}
diff --git a/src/build/core/ExpressionToRegister.go b/src/build/core/ExpressionToRegister.go
index 212b7ed..a0ab61f 100644
--- a/src/build/core/ExpressionToRegister.go
+++ b/src/build/core/ExpressionToRegister.go
@@ -1,6 +1,8 @@
 package core
 
 import (
+	"fmt"
+
 	"git.akyoto.dev/cli/q/src/build/asm"
 	"git.akyoto.dev/cli/q/src/build/ast"
 	"git.akyoto.dev/cli/q/src/build/cpu"
@@ -24,8 +26,19 @@ func (f *Function) ExpressionToRegister(node *expression.Expression, register cp
 		return err
 	}
 
-	if len(node.Children) < 2 {
-		return errors.New(errors.MissingOperand, f.File, node.Token.End())
+	if len(node.Children) == 1 {
+		if !node.Token.IsUnaryOperator() {
+			fmt.Println(node.String(f.File.Bytes), node.Token.Kind)
+			return errors.New(errors.MissingOperand, f.File, node.Token.End())
+		}
+
+		err := f.ExpressionToRegister(node.Children[0], register)
+
+		if err != nil {
+			return err
+		}
+
+		return f.ExecuteRegister(node.Token, register)
 	}
 
 	left := node.Children[0]
diff --git a/src/build/token/Kind.go b/src/build/token/Kind.go
index 871e49f..44f0132 100644
--- a/src/build/token/Kind.go
+++ b/src/build/token/Kind.go
@@ -38,8 +38,6 @@ const (
 	Shr                         // >>
 	LogicalAnd                  // &&
 	LogicalOr                   // ||
-	Not                         // ! (unary)
-	Negate                      // - (unary)
 	Equal                       // ==
 	Less                        // <
 	Greater                     // >
@@ -51,6 +49,10 @@ const (
 	Call                        // x()
 	Array                       // [x]
 	Separator                   // ,
+	_unary                      // <unary>
+	Not                         // ! (unary)
+	Negate                      // - (unary)
+	_unaryEnd                   // </unary>
 	_assignments                // <assignments>
 	Assign                      // =
 	AddAssign                   // +=
diff --git a/src/build/token/Token.go b/src/build/token/Token.go
index 99cbe97..caac815 100644
--- a/src/build/token/Token.go
+++ b/src/build/token/Token.go
@@ -43,6 +43,11 @@ func (t Token) IsOperator() bool {
 	return t.Kind > _operators && t.Kind < _operatorsEnd
 }
 
+// IsUnaryOperator returns true if the token is a unary operator.
+func (t Token) IsUnaryOperator() bool {
+	return t.Kind > _unary && t.Kind < _unaryEnd
+}
+
 // Reset resets the token to default values.
 func (t *Token) Reset() {
 	t.Position = 0
diff --git a/src/build/token/Tokenize.go b/src/build/token/Tokenize.go
index 52b3122..9e0f4fa 100644
--- a/src/build/token/Tokenize.go
+++ b/src/build/token/Tokenize.go
@@ -27,7 +27,7 @@ func Tokenize(buffer []byte) List {
 		case '\n':
 			tokens = append(tokens, Token{Kind: NewLine, Position: i, Length: 1})
 		case '-':
-			if len(tokens) == 0 || tokens[len(tokens)-1].IsOperator() || tokens[len(tokens)-1].IsExpressionStart() {
+			if len(tokens) == 0 || tokens[len(tokens)-1].IsOperator() || tokens[len(tokens)-1].IsExpressionStart() || tokens[len(tokens)-1].IsKeyword() {
 				tokens = append(tokens, Token{Kind: Negate, Position: i, Length: 1})
 			} else {
 				if i+1 < Position(len(buffer)) && buffer[i+1] == '=' {
diff --git a/tests/programs/negation.q b/tests/programs/negation.q
new file mode 100644
index 0000000..aea1133
--- /dev/null
+++ b/tests/programs/negation.q
@@ -0,0 +1,7 @@
+main() {
+	syscall(60, f(-32))
+}
+
+f(x) {
+	return -x
+}
\ No newline at end of file
diff --git a/tests/programs_test.go b/tests/programs_test.go
index 82a9d42..204f314 100644
--- a/tests/programs_test.go
+++ b/tests/programs_test.go
@@ -43,6 +43,7 @@ var programs = []struct {
 	{"loop-lifetime", "", "", 0},
 	{"assert", "", "", 1},
 	{"negative", "", "", 32},
+	{"negation", "", "", 32},
 }
 
 func TestPrograms(t *testing.T) {