diff --git a/examples/server/server.q b/examples/server/server.q
index 6ac4ee3..f90c1c7 100644
--- a/examples/server/server.q
+++ b/examples/server/server.q
@@ -1,6 +1,3 @@
-// Open server and client in 2 terminals:
-// [1] q run examples/server
-// [2] curl http://127.0.0.1:8080
 import io
 import net
 import sys
diff --git a/lib/net/net_linux.q b/lib/net/net_linux.q
index 4a025e3..168c8a2 100644
--- a/lib/net/net_linux.q
+++ b/lib/net/net_linux.q
@@ -1,6 +1,6 @@
 import sys
 
-bind(socket int, port int) -> int {
+bind(socket int, port uint16) -> int {
 	addr := new(sys.sockaddr_in)
 	addr.sin_family = 2
 	addr.sin_port = htons(port)
diff --git a/lib/sys/sys_windows.q b/lib/sys/sys_windows.q
index 2523338..59e6769 100644
--- a/lib/sys/sys_windows.q
+++ b/lib/sys/sys_windows.q
@@ -1,12 +1,12 @@
-read(fd int64, buffer *byte, length int64) -> int64 {
+read(fd int, buffer *byte, length int) -> int {
 	fd = kernel32.GetStdHandle(-10 - fd)
-	kernel32.ReadConsole(fd, buffer, length, 0)
+	kernel32.ReadConsole(fd, buffer, uint32(length), 0)
 	return length
 }
 
-write(fd int64, buffer *byte, length int64) -> int64 {
+write(fd int, buffer *byte, length int) -> int {
 	fd = kernel32.GetStdHandle(-10 - fd)
-	kernel32.WriteConsoleA(fd, buffer, length, 0)
+	kernel32.WriteConsoleA(fd, buffer, uint32(length), 0)
 	return length
 }
 
diff --git a/lib/thread/thread_linux.q b/lib/thread/thread_linux.q
index cf4d75a..592207b 100644
--- a/lib/thread/thread_linux.q
+++ b/lib/thread/thread_linux.q
@@ -12,10 +12,8 @@ const clone {
 }
 
 create(func *any) -> int {
-	size := 4096
-	stack := sys.mmap(0, size, 0x1|0x2, 0x02|0x20|0x100|0x20000)
-	stack += size
-	stack -= 8
+	stack := sys.mmap(0, 4096, 0x1|0x2, 0x02|0x20|0x100)
+	stack += 4096 - 8
 	store(stack, 8, core.exit)
 	stack -= 8
 	store(stack, 8, func)
diff --git a/src/core/ArrayElementToRegister.go b/src/core/ArrayElementToRegister.go
index 0dec215..9e58f3e 100644
--- a/src/core/ArrayElementToRegister.go
+++ b/src/core/ArrayElementToRegister.go
@@ -50,8 +50,8 @@ func (f *Function) ArrayElementToRegister(node *expression.Expression, register
 
 		defer f.UseVariable(indexVariable)
 
-		if !types.Is(indexVariable.Type, types.Int) {
-			return nil, errors.New(&errors.TypeMismatch{Encountered: indexVariable.Type.Name(), Expected: types.Int.Name()}, f.File, index.Token.Position)
+		if !types.Is(indexVariable.Type, types.AnyInt) {
+			return nil, errors.New(&errors.TypeMismatch{Encountered: indexVariable.Type.Name(), Expected: types.AnyInt.Name()}, f.File, index.Token.Position)
 		}
 
 		memory.OffsetRegister = indexVariable.Register
@@ -63,8 +63,8 @@ func (f *Function) ArrayElementToRegister(node *expression.Expression, register
 			return nil, err
 		}
 
-		if !types.Is(typ, types.Int) {
-			return nil, errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.Int.Name()}, f.File, index.Token.Position)
+		if !types.Is(typ, types.AnyInt) {
+			return nil, errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.AnyInt.Name()}, f.File, index.Token.Position)
 		}
 
 		memory.OffsetRegister = register
diff --git a/src/core/CompileAssignArray.go b/src/core/CompileAssignArray.go
index 55e33a5..fff34ca 100644
--- a/src/core/CompileAssignArray.go
+++ b/src/core/CompileAssignArray.go
@@ -47,8 +47,8 @@ func (f *Function) CompileAssignArray(node *ast.Assign) error {
 			return err
 		}
 
-		if !types.Is(typ, types.Int) {
-			return errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.Int.Name()}, f.File, index.Token.Position)
+		if !types.Is(typ, types.AnyInt) {
+			return errors.New(&errors.TypeMismatch{Encountered: typ.Name(), Expected: types.AnyInt.Name()}, f.File, index.Token.Position)
 		}
 
 		memory.OffsetRegister = indexRegister
diff --git a/src/core/CompileCall.go b/src/core/CompileCall.go
index 3d4ad40..e9c94b2 100644
--- a/src/core/CompileCall.go
+++ b/src/core/CompileCall.go
@@ -52,6 +52,17 @@ func (f *Function) CompileCall(root *expression.Expression) ([]types.Type, error
 	fn, exists = f.All.Functions[pkg+"."+name]
 
 	if !exists {
+		typ := types.ByName(name, f.Package, f.All.Structs)
+
+		if typ != nil {
+			if len(root.Children) != 2 {
+				return nil, errors.New(&errors.ParameterCountMismatch{Function: name, Count: len(root.Children), ExpectedCount: 1}, f.File, nameNode.Token.End())
+			}
+
+			_, err := f.ExpressionToRegister(root.Children[1], f.CPU.Output[0])
+			return []types.Type{typ}, err
+		}
+
 		return nil, errors.New(&errors.UnknownFunction{Name: name}, f.File, nameNode.Token.Position)
 	}
 
diff --git a/src/core/CompileDefinition.go b/src/core/CompileDefinition.go
index 71d4b73..af96b46 100644
--- a/src/core/CompileDefinition.go
+++ b/src/core/CompileDefinition.go
@@ -6,6 +6,7 @@ import (
 	"git.urbach.dev/cli/q/src/errors"
 	"git.urbach.dev/cli/q/src/expression"
 	"git.urbach.dev/cli/q/src/token"
+	"git.urbach.dev/cli/q/src/types"
 )
 
 // CompileDefinition compiles a variable definition.
@@ -30,6 +31,10 @@ func (f *Function) CompileDefinition(node *ast.Define) error {
 			return errors.New(errors.UntypedExpression, f.File, node.Expression.Token.End())
 		}
 
+		if typ == types.AnyInt {
+			typ = types.Int
+		}
+
 		variable.Type = typ
 		f.AddVariable(variable)
 		return nil
diff --git a/src/core/CompileLen.go b/src/core/CompileLen.go
index 4065d76..4571c38 100644
--- a/src/core/CompileLen.go
+++ b/src/core/CompileLen.go
@@ -9,7 +9,7 @@ import (
 	"git.urbach.dev/cli/q/src/types"
 )
 
-var _len = Function{OutputTypes: []types.Type{types.Int}}
+var _len = Function{OutputTypes: []types.Type{types.AnyInt}}
 
 // CompileLen returns the length of a slice.
 func (f *Function) CompileLen(root *expression.Expression) error {
diff --git a/src/core/ExpressionToMemory.go b/src/core/ExpressionToMemory.go
index f62ba58..8886f6e 100644
--- a/src/core/ExpressionToMemory.go
+++ b/src/core/ExpressionToMemory.go
@@ -48,7 +48,7 @@ func (f *Function) ExpressionToMemory(node *expression.Expression, memory asm.Me
 			// }
 
 			f.MemoryNumber(asm.STORE, memory, number)
-			return types.Int, nil
+			return types.AnyInt, nil
 		}
 	}
 
diff --git a/src/core/ExpressionToRegister.go b/src/core/ExpressionToRegister.go
index 0a3fb29..54d82b2 100644
--- a/src/core/ExpressionToRegister.go
+++ b/src/core/ExpressionToRegister.go
@@ -13,7 +13,7 @@ import (
 func (f *Function) ExpressionToRegister(node *expression.Expression, register cpu.Register) (types.Type, error) {
 	if node.IsFolded {
 		f.RegisterNumber(asm.MOVE, register, node.Value)
-		return types.Int, nil
+		return types.AnyInt, nil
 	}
 
 	if node.IsLeaf() {
diff --git a/src/core/PeriodToRegister.go b/src/core/PeriodToRegister.go
index 2307a43..aeb7675 100644
--- a/src/core/PeriodToRegister.go
+++ b/src/core/PeriodToRegister.go
@@ -14,8 +14,8 @@ import (
 // PeriodToRegister moves a constant or a function address into the given register.
 func (f *Function) PeriodToRegister(node *expression.Expression, register cpu.Register) (types.Type, error) {
 	left := node.Children[0]
-	leftText := left.Token.Text(f.File.Bytes)
 	right := node.Children[1]
+	leftText := left.Token.Text(f.File.Bytes)
 	rightText := right.Token.Text(f.File.Bytes)
 	variable := f.VariableByName(leftText)
 
@@ -44,7 +44,7 @@ func (f *Function) PeriodToRegister(node *expression.Expression, register cpu.Re
 
 		f.SaveRegister(register)
 		f.RegisterNumber(asm.MOVE, register, number)
-		return types.Int, nil
+		return types.AnyInt, nil
 	}
 
 	uniqueName := fmt.Sprintf("%s.%s", leftText, rightText)
diff --git a/src/core/TokenToRegister.go b/src/core/TokenToRegister.go
index e05d9e8..fce74e1 100644
--- a/src/core/TokenToRegister.go
+++ b/src/core/TokenToRegister.go
@@ -53,7 +53,7 @@ func (f *Function) TokenToRegister(t token.Token, register cpu.Register) (types.
 
 		f.SaveRegister(register)
 		f.RegisterNumber(asm.MOVE, register, number)
-		return types.Int, nil
+		return types.AnyInt, nil
 
 	case token.String:
 		data := t.Bytes(f.File.Bytes)
diff --git a/src/types/Common.go b/src/types/Common.go
index 8cab280..124a6bc 100644
--- a/src/types/Common.go
+++ b/src/types/Common.go
@@ -3,6 +3,7 @@ package types
 var (
 	Any        = &Base{name: "any", size: 0}
 	AnyArray   = &Array{Of: Any}
+	AnyInt     = &Base{name: "int"}
 	AnyPointer = &Pointer{To: Any}
 	Bool       = &Base{name: "bool", size: 1}
 	Int64      = &Base{name: "int64", size: 8}
@@ -12,15 +13,15 @@ var (
 	Float64    = &Base{name: "float64", size: 8}
 	Float32    = &Base{name: "float32", size: 4}
 	String     = &Array{Of: Byte}
+	UInt64     = &Base{name: "uint64", size: 8}
+	UInt32     = &Base{name: "uint32", size: 4}
+	UInt16     = &Base{name: "uint16", size: 2}
+	UInt8      = &Base{name: "uint8", size: 1}
 )
 
 var (
-	Byte   = UInt8
-	Int    = Int64
-	Float  = Float64
-	UInt   = Int
-	UInt64 = Int64
-	UInt32 = Int32
-	UInt16 = Int16
-	UInt8  = Int8
+	Byte  = UInt8
+	Float = Float64
+	Int   = Int64
+	UInt  = UInt64
 )
diff --git a/src/types/Is.go b/src/types/Is.go
index 1629454..875df1a 100644
--- a/src/types/Is.go
+++ b/src/types/Is.go
@@ -25,13 +25,11 @@ func Is(a Type, b Type) bool {
 		return true
 	}
 
-	// Temporary hacks
-	if a == Int32 && b == Int64 {
-		return true
-	}
-
-	if a == Int64 && b == Int32 {
-		return true
+	if a == AnyInt {
+		switch b {
+		case Int64, Int32, Int16, Int8, UInt64, UInt32, UInt16, UInt8:
+			return true
+		}
 	}
 
 	return false
diff --git a/src/types/types_test.go b/src/types/types_test.go
index 856c878..e43bcee 100644
--- a/src/types/types_test.go
+++ b/src/types/types_test.go
@@ -13,7 +13,7 @@ func TestName(t *testing.T) {
 	assert.Equal(t, types.AnyPointer.Name(), "*any")
 	assert.Equal(t, (&types.Pointer{To: types.Int}).Name(), "*int64")
 	assert.Equal(t, (&types.Array{Of: types.Int}).Name(), "[]int64")
-	assert.Equal(t, types.String.Name(), "[]int8")
+	assert.Equal(t, types.String.Name(), "[]uint8")
 }
 
 func TestSize(t *testing.T) {
diff --git a/tests/errors_test.go b/tests/errors_test.go
index 6b10e3f..e672684 100644
--- a/tests/errors_test.go
+++ b/tests/errors_test.go
@@ -50,8 +50,8 @@ var errs = []struct {
 	{"MissingParameter3.q", errors.MissingParameter},
 	{"MissingType.q", errors.MissingType},
 	{"ReturnCountMismatch.q", &errors.ReturnCountMismatch{Count: 1, ExpectedCount: 0}},
-	{"TypeMismatch.q", &errors.TypeMismatch{Expected: "*any", Encountered: "int64", ParameterName: "p"}},
-	{"TypeMismatch2.q", &errors.TypeMismatch{Expected: "[]any", Encountered: "int64", ParameterName: "array"}},
+	{"TypeMismatch.q", &errors.TypeMismatch{Expected: "*any", Encountered: "int", ParameterName: "p"}},
+	{"TypeMismatch2.q", &errors.TypeMismatch{Expected: "[]any", Encountered: "int", ParameterName: "array"}},
 	{"UnknownFunction.q", &errors.UnknownFunction{Name: "unknown"}},
 	{"UnknownFunction2.q", &errors.UnknownFunction{Name: "f"}},
 	{"UnknownIdentifier.q", &errors.UnknownIdentifier{Name: "x"}},
diff --git a/tests/programs/cast.q b/tests/programs/cast.q
new file mode 100644
index 0000000..8eb8ae4
--- /dev/null
+++ b/tests/programs/cast.q
@@ -0,0 +1,8 @@
+main() {
+	x := byte(42)
+	assert f(x) == 42
+}
+
+f(x byte) -> byte {
+	return x
+}
\ No newline at end of file
diff --git a/tests/programs_test.go b/tests/programs_test.go
index 2650a88..2f15d5f 100644
--- a/tests/programs_test.go
+++ b/tests/programs_test.go
@@ -67,6 +67,7 @@ var programs = []struct {
 	{"index-dynamic", 0},
 	{"struct", 0},
 	{"len", 0},
+	{"cast", 0},
 }
 
 func TestPrograms(t *testing.T) {