diff --git a/context.go b/context.go
index 45e1b32..f281db2 100644
--- a/context.go
+++ b/context.go
@@ -21,7 +21,7 @@ type Context struct {
 // Instead, boolean values are stored as integers 0 (false) and 1 (true).
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultBool(value bool) {
+func (c Context) ResultBool(value bool) {
 	var i int64
 	if value {
 		i = 1
@@ -32,14 +32,14 @@ func (c *Context) ResultBool(value bool) {
 // ResultInt sets the result of the function to an int.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultInt(value int) {
+func (c Context) ResultInt(value int) {
 	c.ResultInt64(int64(value))
 }
 
 // ResultInt64 sets the result of the function to an int64.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultInt64(value int64) {
+func (c Context) ResultInt64(value int64) {
 	c.call(c.api.resultInteger,
 		uint64(c.handle), uint64(value))
 }
@@ -47,7 +47,7 @@ func (c *Context) ResultInt64(value int64) {
 // ResultFloat sets the result of the function to a float64.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultFloat(value float64) {
+func (c Context) ResultFloat(value float64) {
 	c.call(c.api.resultFloat,
 		uint64(c.handle), math.Float64bits(value))
 }
@@ -55,7 +55,7 @@ func (c *Context) ResultFloat(value float64) {
 // ResultText sets the result of the function to a string.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultText(value string) {
+func (c Context) ResultText(value string) {
 	ptr := c.newString(value)
 	c.call(c.api.resultText,
 		uint64(c.handle), uint64(ptr), uint64(len(value)),
@@ -66,7 +66,7 @@ func (c *Context) ResultText(value string) {
 // Returning a nil slice is the same as calling [Context.ResultNull].
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultBlob(value []byte) {
+func (c Context) ResultBlob(value []byte) {
 	ptr := c.newBytes(value)
 	c.call(c.api.resultBlob,
 		uint64(c.handle), uint64(ptr), uint64(len(value)),
@@ -76,7 +76,7 @@ func (c *Context) ResultBlob(value []byte) {
 // BindZeroBlob sets the result of the function to a zero-filled, length n BLOB.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultZeroBlob(n int64) {
+func (c Context) ResultZeroBlob(n int64) {
 	c.call(c.api.resultZeroBlob,
 		uint64(c.handle), uint64(n))
 }
@@ -84,7 +84,7 @@ func (c *Context) ResultZeroBlob(n int64) {
 // ResultNull sets the result of the function to NULL.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultNull() {
+func (c Context) ResultNull() {
 	c.call(c.api.resultNull,
 		uint64(c.handle))
 }
@@ -92,7 +92,7 @@ func (c *Context) ResultNull() {
 // ResultTime sets the result of the function to a [time.Time].
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultTime(value time.Time, format TimeFormat) {
+func (c Context) ResultTime(value time.Time, format TimeFormat) {
 	if format == TimeFormatDefault {
 		c.resultRFC3339Nano(value)
 		return
@@ -109,7 +109,7 @@ func (c *Context) ResultTime(value time.Time, format TimeFormat) {
 	}
 }
 
-func (c *Context) resultRFC3339Nano(value time.Time) {
+func (c Context) resultRFC3339Nano(value time.Time) {
 	const maxlen = uint64(len(time.RFC3339Nano))
 
 	ptr := c.new(maxlen)
@@ -124,7 +124,7 @@ func (c *Context) resultRFC3339Nano(value time.Time) {
 // ResultError sets the result of the function an error.
 //
 // https://www.sqlite.org/c3ref/result_blob.html
-func (c *Context) ResultError(err error) {
+func (c Context) ResultError(err error) {
 	if errors.Is(err, NOMEM) {
 		c.call(c.api.resultErrorMem, uint64(c.handle))
 		return
@@ -137,7 +137,7 @@ func (c *Context) ResultError(err error) {
 
 	str := err.Error()
 	ptr := c.newString(str)
-	c.call(c.api.resultBlob,
+	c.call(c.api.resultError,
 		uint64(c.handle), uint64(ptr), uint64(len(str)))
 	c.free(ptr)
 
@@ -152,6 +152,6 @@ func (c *Context) ResultError(err error) {
 	}
 	if code != 0 {
 		c.call(c.api.resultErrorCode,
-			uint64(c.handle), uint64(xcode))
+			uint64(c.handle), uint64(code))
 	}
 }
diff --git a/func.go b/func.go
index 3bf73ae..92f9a1f 100644
--- a/func.go
+++ b/func.go
@@ -56,8 +56,12 @@ func (c *Conn) CreateWindowFunction(name string, nArg int, flag FunctionFlag, fn
 //
 // https://www.sqlite.org/appfunc.html
 type AggregateFunction interface {
+	// Step is invoked to add a row to the current window.
+	// The function arguments, if any, corresponding to the row being added are passed to Step.
 	Step(ctx Context, arg ...Value)
-	Final(ctx Context)
+
+	// Value is invoked to return the current value of the aggregate.
+	Value(ctx Context)
 }
 
 // WindowFunction is the interface an aggregate window function should implement.
@@ -65,7 +69,9 @@ type AggregateFunction interface {
 // https://www.sqlite.org/windowfunctions.html
 type WindowFunction interface {
 	AggregateFunction
-	Value(ctx Context)
+
+	// Inverse is invoked to remove the oldest presently aggregated result of Step from the current window.
+	// The function arguments, if any, are those passed to Step for the row being removed.
 	Inverse(ctx Context, arg ...Value)
 }
 
@@ -92,48 +98,35 @@ func callbackCompare(ctx context.Context, mod api.Module, pApp, nKey1, pKey1, nK
 func callbackFunc(ctx context.Context, mod api.Module, pCtx, nArg, pArg uint32) {
 	module := ctx.Value(moduleKey{}).(*module)
 	fn := callbackHandle(module, pCtx).(func(ctx Context, arg ...Value))
-	fn(Context{
-		module: module,
-		handle: pCtx,
-	}, callbackArgs(module, nArg, pArg)...)
+	fn(Context{module, pCtx}, callbackArgs(module, nArg, pArg)...)
 }
 
 func callbackStep(ctx context.Context, mod api.Module, pCtx, nArg, pArg uint32) {
 	module := ctx.Value(moduleKey{}).(*module)
 	fn := callbackAggregate(module, pCtx, nil).(AggregateFunction)
-	fn.Step(Context{
-		module: module,
-		handle: pCtx,
-	}, callbackArgs(module, nArg, pArg)...)
+	fn.Step(Context{module, pCtx}, callbackArgs(module, nArg, pArg)...)
 }
 
 func callbackFinal(ctx context.Context, mod api.Module, pCtx uint32) {
 	var handle uint32
 	module := ctx.Value(moduleKey{}).(*module)
 	fn := callbackAggregate(module, pCtx, &handle).(AggregateFunction)
-	fn.Final(Context{
-		module: module,
-		handle: pCtx,
-	})
-	util.DelHandle(ctx, handle)
+	fn.Value(Context{module, pCtx})
+	if err := util.DelHandle(ctx, handle); err != nil {
+		Context{module, pCtx}.ResultError(err)
+	}
 }
 
 func callbackValue(ctx context.Context, mod api.Module, pCtx uint32) {
 	module := ctx.Value(moduleKey{}).(*module)
-	fn := callbackAggregate(module, pCtx, nil).(WindowFunction)
-	fn.Value(Context{
-		module: module,
-		handle: pCtx,
-	})
+	fn := callbackAggregate(module, pCtx, nil).(AggregateFunction)
+	fn.Value(Context{module, pCtx})
 }
 
 func callbackInverse(ctx context.Context, mod api.Module, pCtx, nArg, pArg uint32) {
 	module := ctx.Value(moduleKey{}).(*module)
 	fn := callbackAggregate(module, pCtx, nil).(WindowFunction)
-	fn.Inverse(Context{
-		module: module,
-		handle: pCtx,
-	}, callbackArgs(module, nArg, pArg)...)
+	fn.Inverse(Context{module, pCtx}, callbackArgs(module, nArg, pArg)...)
 }
 
 func callbackHandle(module *module, pCtx uint32) any {
@@ -141,18 +134,21 @@ func callbackHandle(module *module, pCtx uint32) any {
 	return util.GetHandle(module.ctx, pApp)
 }
 
-func callbackAggregate(module *module, pCtx uint32, delete *uint32) any {
+func callbackAggregate(module *module, pCtx uint32, close *uint32) any {
+	// On close, we're getting rid of the handle.
+	// Don't allocate space to store it.
 	var size uint64
-	if delete == nil {
+	if close == nil {
 		size = ptrlen
 	}
 	ptr := uint32(module.call(module.api.aggregateCtx, uint64(pCtx), size))
 
-	if ptr != 0 {
+	// Try loading the handle, if we already have one, or want a new one.
+	if ptr != 0 || size != 0 {
 		if handle := util.ReadUint32(module.mod, ptr); handle != 0 {
 			fn := util.GetHandle(module.ctx, handle)
-			if delete != nil {
-				*delete = handle
+			if close != nil {
+				*close = handle
 			}
 			if fn != nil {
 				return fn
@@ -160,6 +156,7 @@ func callbackAggregate(module *module, pCtx uint32, delete *uint32) any {
 		}
 	}
 
+	// Create a new aggregate and store the handle.
 	fn := callbackHandle(module, pCtx).(func() AggregateFunction)()
 	if ptr != 0 {
 		util.WriteUint32(module.mod, ptr, util.AddHandle(module.ctx, fn))
diff --git a/func_win_test.go b/func_win_test.go
index 13ba5d2..87c28e2 100644
--- a/func_win_test.go
+++ b/func_win_test.go
@@ -61,18 +61,12 @@ func ExampleConn_CreateWindowFunction() {
 	// 0
 }
 
-type countASCII struct {
-	result int
-}
+type countASCII struct{ result int }
 
 func newASCIICounter() sqlite3.AggregateFunction {
 	return &countASCII{}
 }
 
-func (f *countASCII) Final(ctx sqlite3.Context) {
-	f.Value(ctx)
-}
-
 func (f *countASCII) Value(ctx sqlite3.Context) {
 	ctx.ResultInt(f.result)
 }
diff --git a/value.go b/value.go
index c98d3a0..a542412 100644
--- a/value.go
+++ b/value.go
@@ -18,7 +18,7 @@ type Value struct {
 // Type returns the initial [Datatype] of the value.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Type() Datatype {
+func (v Value) Type() Datatype {
 	r := v.call(v.api.valueType, uint64(v.handle))
 	return Datatype(r)
 }
@@ -29,7 +29,7 @@ func (v *Value) Type() Datatype {
 // with 0 converted to false and any other value to true.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Bool() bool {
+func (v Value) Bool() bool {
 	if i := v.Int64(); i != 0 {
 		return true
 	}
@@ -39,14 +39,14 @@ func (v *Value) Bool() bool {
 // Int returns the value as an int.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Int() int {
+func (v Value) Int() int {
 	return int(v.Int64())
 }
 
 // Int64 returns the value as an int64.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Int64() int64 {
+func (v Value) Int64() int64 {
 	r := v.call(v.api.valueInteger, uint64(v.handle))
 	return int64(r)
 }
@@ -54,7 +54,7 @@ func (v *Value) Int64() int64 {
 // Float returns the value as a float64.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Float() float64 {
+func (v Value) Float() float64 {
 	r := v.call(v.api.valueFloat, uint64(v.handle))
 	return math.Float64frombits(r)
 }
@@ -62,7 +62,7 @@ func (v *Value) Float() float64 {
 // Time returns the value as a [time.Time].
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Time(format TimeFormat) time.Time {
+func (v Value) Time(format TimeFormat) time.Time {
 	var a any
 	switch v.Type() {
 	case INTEGER:
@@ -83,7 +83,7 @@ func (v *Value) Time(format TimeFormat) time.Time {
 // Text returns the value as a string.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Text() string {
+func (v Value) Text() string {
 	return string(v.RawText())
 }
 
@@ -91,7 +91,7 @@ func (v *Value) Text() string {
 // the value as a []byte.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) Blob(buf []byte) []byte {
+func (v Value) Blob(buf []byte) []byte {
 	return append(buf, v.RawBlob()...)
 }
 
@@ -100,7 +100,7 @@ func (v *Value) Blob(buf []byte) []byte {
 // subsequent calls to [Value] methods.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) RawText() []byte {
+func (v Value) RawText() []byte {
 	r := v.call(v.api.valueText, uint64(v.handle))
 	return v.rawBytes(uint32(r))
 }
@@ -110,12 +110,12 @@ func (v *Value) RawText() []byte {
 // subsequent calls to [Value] methods.
 //
 // https://www.sqlite.org/c3ref/value_blob.html
-func (v *Value) RawBlob() []byte {
+func (v Value) RawBlob() []byte {
 	r := v.call(v.api.valueBlob, uint64(v.handle))
 	return v.rawBytes(uint32(r))
 }
 
-func (v *Value) rawBytes(ptr uint32) []byte {
+func (v Value) rawBytes(ptr uint32) []byte {
 	if ptr == 0 {
 		return nil
 	}
diff --git a/vfs/api.go b/vfs/api.go
index 7425096..158f173 100644
--- a/vfs/api.go
+++ b/vfs/api.go
@@ -15,7 +15,7 @@ type VFS interface {
 	FullPathname(name string) (string, error)
 }
 
-// VFSParams extends VFS to with the ability to handle URI parameters
+// VFSParams extends VFS with the ability to handle URI parameters
 // through the OpenParams method.
 //
 // https://www.sqlite.org/c3ref/uri_boolean.html