diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e0ae9434..ec300a92 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go-version: [1.17.x, 1.18.x]
+        go-version: [1.18.x, 1.19.x]
 
     services:
       redis:
diff --git a/Makefile b/Makefile
index 5dbd7ae8..6399210c 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,8 @@ test: testdeps
 	go test ./... -run=NONE -bench=. -benchmem
 	env GOOS=linux GOARCH=386 go test ./...
 	go vet
+	cd internal/customvet && go build .
+	go vet -vettool ./internal/customvet/customvet
 
 testdeps: testdata/redis/src/redis-server
 
diff --git a/command.go b/command.go
index 319bfba2..d4fc91de 100644
--- a/command.go
+++ b/command.go
@@ -104,7 +104,7 @@ func cmdString(cmd Cmder, val interface{}) string {
 		b = internal.AppendArg(b, val)
 	}
 
-	return internal.String(b)
+	return util.BytesToString(b)
 }
 
 //------------------------------------------------------------------------------
@@ -1093,6 +1093,10 @@ func NewKeyValueSliceCmd(ctx context.Context, args ...interface{}) *KeyValueSlic
 	}
 }
 
+func (cmd *KeyValueSliceCmd) SetVal(val []KeyValue) {
+	cmd.val = val
+}
+
 func (cmd *KeyValueSliceCmd) Val() []KeyValue {
 	return cmd.val
 }
@@ -1288,16 +1292,16 @@ func (cmd *MapStringStringCmd) readReply(rd *proto.Reader) error {
 
 //------------------------------------------------------------------------------
 
-type StringIntMapCmd struct {
+type MapStringIntCmd struct {
 	baseCmd
 
 	val map[string]int64
 }
 
-var _ Cmder = (*StringIntMapCmd)(nil)
+var _ Cmder = (*MapStringIntCmd)(nil)
 
-func NewStringIntMapCmd(ctx context.Context, args ...interface{}) *StringIntMapCmd {
-	return &StringIntMapCmd{
+func NewMapStringIntCmd(ctx context.Context, args ...interface{}) *MapStringIntCmd {
+	return &MapStringIntCmd{
 		baseCmd: baseCmd{
 			ctx:  ctx,
 			args: args,
@@ -1305,23 +1309,23 @@ func NewStringIntMapCmd(ctx context.Context, args ...interface{}) *StringIntMapC
 	}
 }
 
-func (cmd *StringIntMapCmd) SetVal(val map[string]int64) {
+func (cmd *MapStringIntCmd) SetVal(val map[string]int64) {
 	cmd.val = val
 }
 
-func (cmd *StringIntMapCmd) Val() map[string]int64 {
+func (cmd *MapStringIntCmd) Val() map[string]int64 {
 	return cmd.val
 }
 
-func (cmd *StringIntMapCmd) Result() (map[string]int64, error) {
+func (cmd *MapStringIntCmd) Result() (map[string]int64, error) {
 	return cmd.val, cmd.err
 }
 
-func (cmd *StringIntMapCmd) String() string {
+func (cmd *MapStringIntCmd) String() string {
 	return cmdString(cmd, cmd.val)
 }
 
-func (cmd *StringIntMapCmd) readReply(rd *proto.Reader) error {
+func (cmd *MapStringIntCmd) readReply(rd *proto.Reader) error {
 	n, err := rd.ReadMapLen()
 	if err != nil {
 		return err
@@ -3117,6 +3121,10 @@ func NewGeoSearchLocationCmd(
 	}
 }
 
+func (cmd *GeoSearchLocationCmd) SetVal(val []GeoLocation) {
+	cmd.val = val
+}
+
 func (cmd *GeoSearchLocationCmd) Val() []GeoLocation {
 	return cmd.val
 }
@@ -3573,6 +3581,10 @@ func NewMapStringInterfaceCmd(ctx context.Context, args ...interface{}) *MapStri
 	}
 }
 
+func (cmd *MapStringInterfaceCmd) SetVal(val map[string]interface{}) {
+	cmd.val = val
+}
+
 func (cmd *MapStringInterfaceCmd) Val() map[string]interface{} {
 	return cmd.val
 }
@@ -3633,6 +3645,10 @@ func NewMapStringStringSliceCmd(ctx context.Context, args ...interface{}) *MapSt
 	}
 }
 
+func (cmd *MapStringStringSliceCmd) SetVal(val []map[string]string) {
+	cmd.val = val
+}
+
 func (cmd *MapStringStringSliceCmd) Val() []map[string]string {
 	return cmd.val
 }
diff --git a/commands.go b/commands.go
index beb3af2d..57de25b0 100644
--- a/commands.go
+++ b/commands.go
@@ -346,7 +346,7 @@ type Cmdable interface {
 
 	Publish(ctx context.Context, channel string, message interface{}) *IntCmd
 	PubSubChannels(ctx context.Context, pattern string) *StringSliceCmd
-	PubSubNumSub(ctx context.Context, channels ...string) *StringIntMapCmd
+	PubSubNumSub(ctx context.Context, channels ...string) *MapStringIntCmd
 	PubSubNumPat(ctx context.Context) *IntCmd
 
 	ClusterSlots(ctx context.Context) *ClusterSlotsCmd
@@ -3088,14 +3088,14 @@ func (c cmdable) PubSubChannels(ctx context.Context, pattern string) *StringSlic
 	return cmd
 }
 
-func (c cmdable) PubSubNumSub(ctx context.Context, channels ...string) *StringIntMapCmd {
+func (c cmdable) PubSubNumSub(ctx context.Context, channels ...string) *MapStringIntCmd {
 	args := make([]interface{}, 2+len(channels))
 	args[0] = "pubsub"
 	args[1] = "numsub"
 	for i, channel := range channels {
 		args[2+i] = channel
 	}
-	cmd := NewStringIntMapCmd(ctx, args...)
+	cmd := NewMapStringIntCmd(ctx, args...)
 	_ = c(ctx, cmd)
 	return cmd
 }
diff --git a/internal/arg.go b/internal/arg.go
index b97fa0d6..af5f8c93 100644
--- a/internal/arg.go
+++ b/internal/arg.go
@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"strconv"
 	"time"
+
+	"github.com/go-redis/redis/v9/internal/util"
 )
 
 func AppendArg(b []byte, v interface{}) []byte {
@@ -11,7 +13,7 @@ func AppendArg(b []byte, v interface{}) []byte {
 	case nil:
 		return append(b, "<nil>"...)
 	case string:
-		return appendUTF8String(b, Bytes(v))
+		return appendUTF8String(b, util.StringToBytes(v))
 	case []byte:
 		return appendUTF8String(b, v)
 	case int:
diff --git a/internal/customvet/.gitignore b/internal/customvet/.gitignore
new file mode 100644
index 00000000..6341ecb8
--- /dev/null
+++ b/internal/customvet/.gitignore
@@ -0,0 +1 @@
+/customvet
diff --git a/internal/customvet/checks/setval/setval.go b/internal/customvet/checks/setval/setval.go
new file mode 100644
index 00000000..e629f5f7
--- /dev/null
+++ b/internal/customvet/checks/setval/setval.go
@@ -0,0 +1,61 @@
+package setval
+
+import (
+	"go/ast"
+	"go/token"
+	"go/types"
+	"golang.org/x/tools/go/analysis"
+)
+
+var Analyzer = &analysis.Analyzer{
+	Name: "setval",
+	Doc:  "find Cmder types that are missing a SetVal method",
+
+	Run: func(pass *analysis.Pass) (interface{}, error) {
+		cmderTypes := make(map[string]token.Pos)
+		typesWithSetValMethod := make(map[string]bool)
+
+		for _, file := range pass.Files {
+			for _, decl := range file.Decls {
+				funcName, receiverType := parseFuncDecl(decl, pass.TypesInfo)
+
+				switch funcName {
+				case "Result":
+					cmderTypes[receiverType] = decl.Pos()
+				case "SetVal":
+					typesWithSetValMethod[receiverType] = true
+				}
+			}
+		}
+
+		for cmder, pos := range cmderTypes {
+			if !typesWithSetValMethod[cmder] {
+				pass.Reportf(pos, "%s is missing a SetVal method", cmder)
+			}
+		}
+
+		return nil, nil
+	},
+}
+
+func parseFuncDecl(decl ast.Decl, typesInfo *types.Info) (funcName, receiverType string) {
+	funcDecl, ok := decl.(*ast.FuncDecl)
+	if !ok {
+		return "", "" // Not a function declaration.
+	}
+
+	if funcDecl.Recv == nil {
+		return "", "" // Not a method.
+	}
+
+	if len(funcDecl.Recv.List) != 1 {
+		return "", "" // Unexpected number of receiver arguments. (Can this happen?)
+	}
+
+	receiverTypeObj := typesInfo.TypeOf(funcDecl.Recv.List[0].Type)
+	if receiverTypeObj == nil {
+		return "", "" // Unable to determine the receiver type.
+	}
+
+	return funcDecl.Name.Name, receiverTypeObj.String()
+}
diff --git a/internal/customvet/checks/setval/setval_test.go b/internal/customvet/checks/setval/setval_test.go
new file mode 100644
index 00000000..44377439
--- /dev/null
+++ b/internal/customvet/checks/setval/setval_test.go
@@ -0,0 +1,12 @@
+package setval_test
+
+import (
+	"github.com/go-redis/redis/internal/customvet/checks/setval"
+	"golang.org/x/tools/go/analysis/analysistest"
+	"testing"
+)
+
+func Test(t *testing.T) {
+	testdata := analysistest.TestData()
+	analysistest.Run(t, testdata, setval.Analyzer, "a")
+}
diff --git a/internal/customvet/checks/setval/testdata/src/a/a.go b/internal/customvet/checks/setval/testdata/src/a/a.go
new file mode 100644
index 00000000..035cb5d3
--- /dev/null
+++ b/internal/customvet/checks/setval/testdata/src/a/a.go
@@ -0,0 +1,29 @@
+package a
+
+type GoodCmd struct {
+	val int
+}
+
+func (c *GoodCmd) SetVal(val int) {
+	c.val = val
+}
+
+func (c *GoodCmd) Result() (int, error) {
+	return c.val, nil
+}
+
+type BadCmd struct {
+	val int
+}
+
+func (c *BadCmd) Result() (int, error) { // want "\\*a.BadCmd is missing a SetVal method"
+	return c.val, nil
+}
+
+type NotACmd struct {
+	val int
+}
+
+func (c *NotACmd) Val() int {
+	return c.val
+}
diff --git a/internal/customvet/go.mod b/internal/customvet/go.mod
new file mode 100644
index 00000000..d3bce547
--- /dev/null
+++ b/internal/customvet/go.mod
@@ -0,0 +1,10 @@
+module github.com/go-redis/redis/internal/customvet
+
+go 1.17
+
+require golang.org/x/tools v0.1.12
+
+require (
+	golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 // indirect
+	golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f // indirect
+)
diff --git a/internal/customvet/go.sum b/internal/customvet/go.sum
new file mode 100644
index 00000000..3ddae732
--- /dev/null
+++ b/internal/customvet/go.sum
@@ -0,0 +1,26 @@
+github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4 h1:6zppjxzCulZykYSLyVDYbneBfbaBIQPYMevg0bEwv2s=
+golang.org/x/mod v0.6.0-dev.0.20220419223038-86c51ed26bb4/go.mod h1:jJ57K6gSWd91VN4djpZkiMVwK6gcyfeH4XE8wZrZaV4=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/net v0.0.0-20220722155237-a158d28d115b/go.mod h1:XRhObCWvk6IyKnWLug+ECip1KBveYUHfp+8e9klMJ9c=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f h1:v4INt8xihDGvnrfjMDVXGxw9wrfxYyCjk0KbXjhR55s=
+golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.12 h1:VveCTK38A2rkS8ZqFY25HIDFscX5X9OoEhJd3quQmXU=
+golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/internal/customvet/main.go b/internal/customvet/main.go
new file mode 100644
index 00000000..a6146dcf
--- /dev/null
+++ b/internal/customvet/main.go
@@ -0,0 +1,12 @@
+package main
+
+import (
+	"github.com/go-redis/redis/internal/customvet/checks/setval"
+	"golang.org/x/tools/go/analysis/multichecker"
+)
+
+func main() {
+	multichecker.Main(
+		setval.Analyzer,
+	)
+}
diff --git a/internal/safe.go b/internal/safe.go
deleted file mode 100644
index fd2f4340..00000000
--- a/internal/safe.go
+++ /dev/null
@@ -1,12 +0,0 @@
-//go:build appengine
-// +build appengine
-
-package internal
-
-func String(b []byte) string {
-	return string(b)
-}
-
-func Bytes(s string) []byte {
-	return []byte(s)
-}
diff --git a/internal/unsafe.go b/internal/unsafe.go
deleted file mode 100644
index 9f2e418f..00000000
--- a/internal/unsafe.go
+++ /dev/null
@@ -1,21 +0,0 @@
-//go:build !appengine
-// +build !appengine
-
-package internal
-
-import "unsafe"
-
-// String converts byte slice to string.
-func String(b []byte) string {
-	return *(*string)(unsafe.Pointer(&b))
-}
-
-// Bytes converts string to byte slice.
-func Bytes(s string) []byte {
-	return *(*[]byte)(unsafe.Pointer(
-		&struct {
-			string
-			Cap int
-		}{s, len(s)},
-	))
-}
diff --git a/iterator.go b/iterator.go
index 2f8bc2be..cd1a8285 100644
--- a/iterator.go
+++ b/iterator.go
@@ -2,30 +2,21 @@ package redis
 
 import (
 	"context"
-	"sync"
 )
 
 // ScanIterator is used to incrementally iterate over a collection of elements.
-// It's safe for concurrent use by multiple goroutines.
 type ScanIterator struct {
-	mu  sync.Mutex // protects Scanner and pos
 	cmd *ScanCmd
 	pos int
 }
 
 // Err returns the last iterator error, if any.
 func (it *ScanIterator) Err() error {
-	it.mu.Lock()
-	err := it.cmd.Err()
-	it.mu.Unlock()
-	return err
+	return it.cmd.Err()
 }
 
 // Next advances the cursor and returns true if more values can be read.
 func (it *ScanIterator) Next(ctx context.Context) bool {
-	it.mu.Lock()
-	defer it.mu.Unlock()
-
 	// Instantly return on errors.
 	if it.cmd.Err() != nil {
 		return false
@@ -68,10 +59,8 @@ func (it *ScanIterator) Next(ctx context.Context) bool {
 // Val returns the key/field at the current cursor position.
 func (it *ScanIterator) Val() string {
 	var v string
-	it.mu.Lock()
 	if it.cmd.Err() == nil && it.pos > 0 && it.pos <= len(it.cmd.page) {
 		v = it.cmd.page[it.pos-1]
 	}
-	it.mu.Unlock()
 	return v
 }
diff --git a/result.go b/result.go
index 9401dfee..44741b01 100644
--- a/result.go
+++ b/result.go
@@ -83,16 +83,16 @@ func NewBoolSliceResult(val []bool, err error) *BoolSliceCmd {
 }
 
 // NewStringStringMapResult returns a StringStringMapCmd initialised with val and err for testing.
-func NewStringStringMapResult(val map[string]string, err error) *MapStringStringCmd {
+func NewMapStringStringResult(val map[string]string, err error) *MapStringStringCmd {
 	var cmd MapStringStringCmd
 	cmd.val = val
 	cmd.SetErr(err)
 	return &cmd
 }
 
-// NewStringIntMapCmdResult returns a StringIntMapCmd initialised with val and err for testing.
-func NewStringIntMapCmdResult(val map[string]int64, err error) *StringIntMapCmd {
-	var cmd StringIntMapCmd
+// NewMapStringIntCmdResult returns a MapStringIntCmd initialised with val and err for testing.
+func NewMapStringIntCmdResult(val map[string]int64, err error) *MapStringIntCmd {
+	var cmd MapStringIntCmd
 	cmd.val = val
 	cmd.SetErr(err)
 	return &cmd