diff --git a/lib/io/io.q b/lib/io/io.q
index 5c195a4..4b34566 100644
--- a/lib/io/io.q
+++ b/lib/io/io.q
@@ -1,15 +1,21 @@
 import sys
 
+const std {
+	in  0
+	out 1
+	err 2
+}
+
 in(buffer []Int8) -> Int {
-	return sys.read(0, buffer, len(buffer))
+	return sys.read(std.in, buffer, len(buffer))
 }
 
 out(buffer []Int8) -> Int {
-	return sys.write(1, buffer, len(buffer))
+	return sys.write(std.out, buffer, len(buffer))
 }
 
 error(buffer []Int8) -> Int {
-	return sys.write(2, buffer, len(buffer))
+	return sys.write(std.err, buffer, len(buffer))
 }
 
 read(fd Int, buffer []Int8) -> Int {
diff --git a/lib/mem/alloc_linux.q b/lib/mem/alloc_linux.q
index 9b9878b..8ade3e6 100644
--- a/lib/mem/alloc_linux.q
+++ b/lib/mem/alloc_linux.q
@@ -1,7 +1,17 @@
 import sys
 
+const prot {
+	read  0x1
+	write 0x2
+}
+
+const map {
+	private   0x02
+	anonymous 0x20
+}
+
 alloc(length Int) -> []Int8 {
-	x := sys.mmap(0, length+8, 0x1|0x2, 0x02|0x20)
+	x := sys.mmap(0, length+8, prot.read|prot.write, map.private|map.anonymous)
 
 	if x < 0x1000 {
 		return x
diff --git a/lib/mem/alloc_mac.q b/lib/mem/alloc_mac.q
index 128d40c..cdfbe86 100644
--- a/lib/mem/alloc_mac.q
+++ b/lib/mem/alloc_mac.q
@@ -1,7 +1,17 @@
 import sys
 
+const prot {
+	read  0x1
+	write 0x2
+}
+
+const map {
+	private   0x02
+	anonymous 0x1000
+}
+
 alloc(length Int) -> []Int8 {
-	x := sys.mmap(0, length+8, 0x1|0x2, 0x02|0x1000)
+	x := sys.mmap(0, length+8, prot.read|prot.write, map.private|map.anonymous)
 
 	if x < 0x1000 {
 		return x
diff --git a/lib/mem/alloc_windows.q b/lib/mem/alloc_windows.q
index 50bb75d..3167a43 100644
--- a/lib/mem/alloc_windows.q
+++ b/lib/mem/alloc_windows.q
@@ -1,7 +1,16 @@
 import sys
 
+const page {
+	readwrite 0x0004
+}
+
+const mem {
+	commit  0x1000
+	reserve 0x2000
+}
+
 alloc(length Int) -> []Int8 {
-	x := sys.mmap(0, length+8, 0x0004, 0x3000)
+	x := sys.mmap(0, length+8, page.readwrite, mem.commit|mem.reserve)
 
 	if x < 0x1000 {
 		return x
diff --git a/lib/sys/mem_windows.q b/lib/sys/mem_windows.q
index 79b093a..97772e9 100644
--- a/lib/sys/mem_windows.q
+++ b/lib/sys/mem_windows.q
@@ -3,10 +3,14 @@ extern kernel32 {
 	VirtualFree(address *Any, length Int, type Int) -> Bool
 }
 
+const mem {
+	decommit 0x4000
+}
+
 mmap(address Int, length Int, protection Int, flags Int) -> *Any {
 	return kernel32.VirtualAlloc(address, length, flags, protection)
 }
 
 munmap(address *Any, length Int) -> Int {
-	return kernel32.VirtualFree(address, length, 0x4000)
+	return kernel32.VirtualFree(address, length, mem.decommit)
 }
\ No newline at end of file
diff --git a/src/build/Build.go b/src/build/Build.go
index 9784a97..64e1190 100644
--- a/src/build/Build.go
+++ b/src/build/Build.go
@@ -23,8 +23,8 @@ func New(files ...string) *Build {
 
 // Run compiles the input files.
 func (build *Build) Run() (compiler.Result, error) {
-	files, functions, structs, errors := scanner.Scan(build.Files)
-	return compiler.Compile(files, functions, structs, errors)
+	constants, files, functions, structs, errors := scanner.Scan(build.Files)
+	return compiler.Compile(constants, files, functions, structs, errors)
 }
 
 // Executable returns the path to the executable.
diff --git a/src/compiler/Compile.go b/src/compiler/Compile.go
index d66ce52..f964d78 100644
--- a/src/compiler/Compile.go
+++ b/src/compiler/Compile.go
@@ -8,13 +8,14 @@ import (
 )
 
 // Compile waits for the scan to finish and compiles all functions.
-func Compile(files <-chan *fs.File, functions <-chan *core.Function, structs <-chan *types.Struct, errs <-chan error) (Result, error) {
+func Compile(constants <-chan *core.Constant, files <-chan *fs.File, functions <-chan *core.Function, structs <-chan *types.Struct, errs <-chan error) (Result, error) {
 	result := Result{}
 	allFiles := make([]*fs.File, 0, 8)
 	allFunctions := make(map[string]*core.Function, 32)
 	allStructs := make(map[string]*types.Struct, 8)
+	allConstants := make(map[string]*core.Constant, 8)
 
-	for functions != nil || structs != nil || files != nil || errs != nil {
+	for constants != nil || files != nil || functions != nil || structs != nil || errs != nil {
 		select {
 		case function, ok := <-functions:
 			if !ok {
@@ -24,6 +25,7 @@ func Compile(files <-chan *fs.File, functions <-chan *core.Function, structs <-c
 
 			function.Functions = allFunctions
 			function.Structs = allStructs
+			function.Constants = allConstants
 			allFunctions[function.UniqueName] = function
 
 		case structure, ok := <-structs:
@@ -42,6 +44,14 @@ func Compile(files <-chan *fs.File, functions <-chan *core.Function, structs <-c
 
 			allFiles = append(allFiles, file)
 
+		case constant, ok := <-constants:
+			if !ok {
+				constants = nil
+				continue
+			}
+
+			allConstants[constant.Name] = constant
+
 		case err, ok := <-errs:
 			if !ok {
 				errs = nil
diff --git a/src/core/Constant.go b/src/core/Constant.go
new file mode 100644
index 0000000..1156e05
--- /dev/null
+++ b/src/core/Constant.go
@@ -0,0 +1,13 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/fs"
+	"git.akyoto.dev/cli/q/src/token"
+)
+
+// Constant registers a single value to be accessible under a descriptive name.
+type Constant struct {
+	Name  string
+	Value token.Token
+	File  *fs.File
+}
diff --git a/src/core/ExpressionToRegister.go b/src/core/ExpressionToRegister.go
index 4e52cc9..d1a85ec 100644
--- a/src/core/ExpressionToRegister.go
+++ b/src/core/ExpressionToRegister.go
@@ -86,11 +86,22 @@ func (f *Function) ExpressionToRegister(node *expression.Expression, register cp
 
 	if node.Token.Kind == token.Period {
 		left := node.Children[0]
-		name := left.Token.Text(f.File.Bytes)
-		variable := f.VariableByName(name)
+		leftText := left.Token.Text(f.File.Bytes)
 		right := node.Children[1]
-		name = right.Token.Text(f.File.Bytes)
-		field := variable.Type.(*types.Pointer).To.(*types.Struct).FieldByName(name)
+		rightText := right.Token.Text(f.File.Bytes)
+		variable := f.VariableByName(leftText)
+
+		if variable == nil {
+			constant, isConst := f.Constants[f.Package+"."+leftText+"."+rightText]
+
+			if isConst {
+				return f.TokenToRegister(constant.Value, register)
+			}
+
+			return nil, errors.New(&errors.UnknownIdentifier{Name: leftText}, f.File, left.Token.Position)
+		}
+
+		field := variable.Type.(*types.Pointer).To.(*types.Struct).FieldByName(rightText)
 		f.MemoryRegister(asm.LOAD, asm.Memory{Base: variable.Register, Offset: int8(field.Offset), Length: byte(field.Type.Size())}, register)
 		return field.Type, nil
 	}
diff --git a/src/core/Function.go b/src/core/Function.go
index 5565dea..956956c 100644
--- a/src/core/Function.go
+++ b/src/core/Function.go
@@ -21,6 +21,7 @@ type Function struct {
 	OutputTypes []types.Type
 	Functions   map[string]*Function
 	Structs     map[string]*types.Struct
+	Constants   map[string]*Constant
 	DLLs        dll.List
 	Err         error
 	deferred    []func()
diff --git a/src/errors/Common.go b/src/errors/Common.go
index c313c86..04638d8 100644
--- a/src/errors/Common.go
+++ b/src/errors/Common.go
@@ -2,6 +2,7 @@ package errors
 
 var (
 	EmptySwitch                = &Base{"Empty switch"}
+	ExpectedConstName          = &Base{"Expected a name for the const group"}
 	ExpectedFunctionParameters = &Base{"Expected function parameters"}
 	ExpectedFunctionDefinition = &Base{"Expected function definition"}
 	ExpectedIfBeforeElse       = &Base{"Expected an 'if' block before 'else'"}
diff --git a/src/scanner/Scan.go b/src/scanner/Scan.go
index fdb3354..f745619 100644
--- a/src/scanner/Scan.go
+++ b/src/scanner/Scan.go
@@ -10,8 +10,9 @@ import (
 )
 
 // Scan scans the list of files.
-func Scan(files []string) (<-chan *fs.File, <-chan *core.Function, <-chan *types.Struct, <-chan error) {
+func Scan(files []string) (chan *core.Constant, <-chan *fs.File, <-chan *core.Function, <-chan *types.Struct, <-chan error) {
 	scanner := Scanner{
+		constants: make(chan *core.Constant),
 		files:     make(chan *fs.File),
 		functions: make(chan *core.Function),
 		structs:   make(chan *types.Struct),
@@ -22,11 +23,12 @@ func Scan(files []string) (<-chan *fs.File, <-chan *core.Function, <-chan *types
 		scanner.queueDirectory(filepath.Join(config.Library, "mem"), "mem")
 		scanner.queue(files...)
 		scanner.group.Wait()
+		close(scanner.constants)
 		close(scanner.files)
 		close(scanner.functions)
 		close(scanner.structs)
 		close(scanner.errors)
 	}()
 
-	return scanner.files, scanner.functions, scanner.structs, scanner.errors
+	return scanner.constants, scanner.files, scanner.functions, scanner.structs, scanner.errors
 }
diff --git a/src/scanner/Scanner.go b/src/scanner/Scanner.go
index 97847bd..9bb05fa 100644
--- a/src/scanner/Scanner.go
+++ b/src/scanner/Scanner.go
@@ -10,6 +10,7 @@ import (
 
 // Scanner is used to scan files before the actual compilation step.
 type Scanner struct {
+	constants chan *core.Constant
 	files     chan *fs.File
 	functions chan *core.Function
 	structs   chan *types.Struct
diff --git a/src/scanner/scanConst.go b/src/scanner/scanConst.go
new file mode 100644
index 0000000..f382813
--- /dev/null
+++ b/src/scanner/scanConst.go
@@ -0,0 +1,47 @@
+package scanner
+
+import (
+	"git.akyoto.dev/cli/q/src/core"
+	"git.akyoto.dev/cli/q/src/errors"
+	"git.akyoto.dev/cli/q/src/fs"
+	"git.akyoto.dev/cli/q/src/token"
+)
+
+// scanConst scans a block of constants.
+func (s *Scanner) scanConst(file *fs.File, tokens token.List, i int) (int, error) {
+	i++
+
+	if tokens[i].Kind != token.Identifier {
+		return i, errors.New(errors.ExpectedConstName, file, tokens[i].Position)
+	}
+
+	groupName := tokens[i].Text(file.Bytes)
+	i++
+
+	if tokens[i].Kind != token.BlockStart {
+		return i, errors.New(errors.MissingBlockStart, file, tokens[i].Position)
+	}
+
+	i++
+
+	for i < len(tokens) {
+		if tokens[i].Kind == token.Identifier {
+			name := tokens[i].Text(file.Bytes)
+			i++
+
+			s.constants <- &core.Constant{
+				Name:  file.Package + "." + groupName + "." + name,
+				Value: tokens[i],
+				File:  file,
+			}
+		}
+
+		if tokens[i].Kind == token.BlockEnd {
+			return i, nil
+		}
+
+		i++
+	}
+
+	return i, errors.New(errors.MissingBlockEnd, file, tokens[i].Position)
+}
diff --git a/src/scanner/scanExtern.go b/src/scanner/scanExtern.go
index e4dc19d..4e4e7e8 100644
--- a/src/scanner/scanExtern.go
+++ b/src/scanner/scanExtern.go
@@ -22,7 +22,6 @@ func (s *Scanner) scanExtern(file *fs.File, tokens token.List, i int) (int, erro
 	}
 
 	i++
-	closed := false
 
 	for i < len(tokens) {
 		if tokens[i].Kind == token.Identifier {
@@ -39,16 +38,11 @@ func (s *Scanner) scanExtern(file *fs.File, tokens token.List, i int) (int, erro
 		}
 
 		if tokens[i].Kind == token.BlockEnd {
-			closed = true
-			break
+			return i, nil
 		}
 
 		i++
 	}
 
-	if !closed {
-		return i, errors.New(errors.MissingBlockEnd, file, tokens[i].Position)
-	}
-
-	return i, nil
+	return i, errors.New(errors.MissingBlockEnd, file, tokens[i].Position)
 }
diff --git a/src/scanner/scanFile.go b/src/scanner/scanFile.go
index 2aae3af..65601f0 100644
--- a/src/scanner/scanFile.go
+++ b/src/scanner/scanFile.go
@@ -39,6 +39,8 @@ func (s *Scanner) scanFile(path string, pkg string) error {
 			i, err = s.scanFunction(file, tokens, i)
 		case token.Extern:
 			i, err = s.scanExtern(file, tokens, i)
+		case token.Const:
+			i, err = s.scanConst(file, tokens, i)
 		case token.EOF:
 			return nil
 		case token.Invalid:
diff --git a/src/token/Kind.go b/src/token/Kind.go
index 6e729e4..200d131 100644
--- a/src/token/Kind.go
+++ b/src/token/Kind.go
@@ -65,6 +65,7 @@ const (
 	___END_OPERATORS___               // </operators>
 	___KEYWORDS___                    // <keywords>
 	Assert                            // assert
+	Const                             // const
 	Else                              // else
 	Extern                            // extern
 	If                                // if
diff --git a/src/token/Tokenize_test.go b/src/token/Tokenize_test.go
index 022115d..b38a5d7 100644
--- a/src/token/Tokenize_test.go
+++ b/src/token/Tokenize_test.go
@@ -25,10 +25,11 @@ func TestFunction(t *testing.T) {
 }
 
 func TestKeyword(t *testing.T) {
-	tokens := token.Tokenize([]byte("assert if import else extern loop return struct switch"))
+	tokens := token.Tokenize([]byte("assert const if import else extern loop return struct switch"))
 
 	expected := []token.Kind{
 		token.Assert,
+		token.Const,
 		token.If,
 		token.Import,
 		token.Else,
diff --git a/src/token/identifier.go b/src/token/identifier.go
index 6b6823b..6973fc6 100644
--- a/src/token/identifier.go
+++ b/src/token/identifier.go
@@ -15,6 +15,8 @@ func identifier(tokens List, buffer []byte, i Position) (List, Position) {
 	switch string(identifier) {
 	case "assert":
 		kind = Assert
+	case "const":
+		kind = Const
 	case "if":
 		kind = If
 	case "else":
diff --git a/tests/programs/const.q b/tests/programs/const.q
new file mode 100644
index 0000000..c947f1a
--- /dev/null
+++ b/tests/programs/const.q
@@ -0,0 +1,12 @@
+const num {
+	one   1
+	two   2
+	three 3
+}
+
+main() {
+	assert num.one == 1
+	assert num.two == 2
+	assert num.three == 3
+	assert num.one + num.two == num.three
+}
\ No newline at end of file
diff --git a/tests/programs_test.go b/tests/programs_test.go
index f3a13cb..23ec235 100644
--- a/tests/programs_test.go
+++ b/tests/programs_test.go
@@ -31,6 +31,7 @@ var programs = []struct {
 	{"binary", "", "", 0},
 	{"octal", "", "", 0},
 	{"hexadecimal", "", "", 0},
+	{"const", "", "", 0},
 	{"array", "", "", 0},
 	{"escape-rune", "", "", 0},
 	{"escape-string", "", "", 0},