diff --git a/cmd/cue/cmd/custom.go b/cmd/cue/cmd/custom.go
index 0474f6e9d..1d06cfa4a 100644
--- a/cmd/cue/cmd/custom.go
+++ b/cmd/cue/cmd/custom.go
@@ -49,8 +49,8 @@ func lookupString(obj cue.Value, key, def string) string {
 // splitLine splits the first line and the rest of the string.
 func splitLine(s string) (line, tail string) {
 	line = s
-	if p := strings.IndexByte(s, '\n'); p >= 0 {
-		line, tail = strings.TrimSpace(s[:p]), strings.TrimSpace(s[p+1:])
+	if before, after, ok := strings.Cut(s, "\n"); ok {
+		line, tail = strings.TrimSpace(before), strings.TrimSpace(after)
 	}
 	return
 }
diff --git a/cue/format/printer.go b/cue/format/printer.go
index 68e5b7c6b..f2ca7e026 100644
--- a/cue/format/printer.go
+++ b/cue/format/printer.go
@@ -401,7 +401,7 @@ func (p *printer) writeString(s string, isLit bool) {
 }
 
 func (p *printer) writeByte(ch byte, n int) {
-	for i := 0; i < n; i++ {
+	for range n {
 		p.output = append(p.output, ch)
 	}
 
@@ -412,7 +412,7 @@ func (p *printer) writeByte(ch byte, n int) {
 		p.pos.Column = 1
 
 		n := p.cfg.Indent + p.indent // include base indentation
-		for i := 0; i < n; i++ {
+		for range n {
 			p.output = append(p.output, '\t')
 		}
 
diff --git a/cue/literal/string.go b/cue/literal/string.go
index 342b91f32..72ceb56d8 100644
--- a/cue/literal/string.go
+++ b/cue/literal/string.go
@@ -405,7 +405,7 @@ func unquoteChar(s string, info QuoteInfo) (value rune, multibyte bool, tail str
 			err = errSyntax
 			return
 		}
-		for j := 0; j < 2; j++ { // one digit already; two more
+		for j := range 2 { // one digit already; two more
 			x := rune(s[j]) - '0'
 			if x < 0 || x > 7 {
 				err = errSyntax
diff --git a/cue/load/loader_test.go b/cue/load/loader_test.go
index dffff0bdf..450cd3c5e 100644
--- a/cue/load/loader_test.go
+++ b/cue/load/loader_test.go
@@ -855,7 +855,7 @@ func TestLoadInstancesConcurrent(t *testing.T) {
 
 func race(t *testing.T, f func() error) {
 	var wg sync.WaitGroup
-	for i := 0; i < 2; i++ {
+	for range 2 {
 		wg.Add(1)
 		go func() {
 			if err := f(); err != nil {
diff --git a/cue/load/search.go b/cue/load/search.go
index aa370073a..5782fab16 100644
--- a/cue/load/search.go
+++ b/cue/load/search.go
@@ -147,8 +147,8 @@ func (l *loader) matchPackagesInFS(pattern, pkgName string) *match {
 	//
 	// TODO this logic entirely ignores the pattern that's
 	// after the "...". See cuelang.org/issue/3212
-	i := strings.Index(pattern, "...")
-	dir, _ := path.Split(pattern[:i])
+	before, _, _ := strings.Cut(pattern, "...")
+	dir, _ := path.Split(before)
 
 	root := l.abs(dir)
 
diff --git a/encoding/jsonschema/decode.go b/encoding/jsonschema/decode.go
index 7c671017c..62473dbd0 100644
--- a/encoding/jsonschema/decode.go
+++ b/encoding/jsonschema/decode.go
@@ -855,7 +855,7 @@ func (s0 *state) schemaState(n cue.Value, types cue.Kind, init func(*state)) (ex
 	}
 
 	// do multiple passes over the constraints to ensure they are done in order.
-	for pass := 0; pass < numPhases; pass++ {
+	for pass := range numPhases {
 		s.processMap(n, func(key string, value cue.Value) {
 			if pass == 0 && key == "$ref" {
 				// Before 2019-19, keywords alongside $ref are ignored so keep
diff --git a/internal/anyunique/unique_test.go b/internal/anyunique/unique_test.go
index d2bb665af..d08a24ae5 100644
--- a/internal/anyunique/unique_test.go
+++ b/internal/anyunique/unique_test.go
@@ -284,7 +284,7 @@ func TestStore_Make_RepeatedCalls(t *testing.T) {
 
 	// Make the same value many times
 	var values []anyunique.Handle[string]
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		values = append(values, s.Make("repeated"))
 	}
 
@@ -352,14 +352,14 @@ func TestStore_Make_StressTest(t *testing.T) {
 	n := 10000
 	uniqueMap := make(map[int]anyunique.Handle[int])
 
-	for i := 0; i < n; i++ {
+	for i := range n {
 		u := s.Make(i)
 		uniqueMap[i] = u
 		qt.Assert(t, qt.Equals(u.Value(), i))
 	}
 
 	// Verify all values are stored correctly and re-making gives equal results
-	for i := 0; i < n; i++ {
+	for i := range n {
 		u := s.Make(i)
 		qt.Assert(t, qt.Equals(u, uniqueMap[i]))
 	}
@@ -497,7 +497,7 @@ func TestStore_Make_AlternatingPatterns(t *testing.T) {
 	s := anyunique.New[string](stringHasher{})
 
 	// Alternate between two values many times
-	for i := 0; i < 100; i++ {
+	for range 100 {
 		u1 := s.Make("a")
 		u2 := s.Make("b")
 		u3 := s.Make("a")
diff --git a/internal/astinternal/debug.go b/internal/astinternal/debug.go
index f2e4a21ce..da43916f9 100644
--- a/internal/astinternal/debug.go
+++ b/internal/astinternal/debug.go
@@ -447,33 +447,34 @@ func DebugStr(x interface{}) (out string) {
 		return out
 
 	case *ast.Field:
-		out := DebugStr(v.Label)
+		var out strings.Builder
+		out.WriteString(DebugStr(v.Label))
 		if v.Alias != nil {
-			out += "~"
+			out.WriteString("~")
 			if v.Alias.Label != nil {
 				// Dual form
-				out += "("
-				out += DebugStr(v.Alias.Label)
-				out += ","
-				out += DebugStr(v.Alias.Field)
-				out += ")"
+				out.WriteString("(")
+				out.WriteString(DebugStr(v.Alias.Label))
+				out.WriteString(",")
+				out.WriteString(DebugStr(v.Alias.Field))
+				out.WriteString(")")
 			} else {
 				// Simple form
-				out += DebugStr(v.Alias.Field)
+				out.WriteString(DebugStr(v.Alias.Field))
 			}
 		}
 		if t := v.Constraint; t != token.ILLEGAL {
-			out += t.String()
+			out.WriteString(t.String())
 		}
 		if v.Value != nil {
-			out += ": "
-			out += DebugStr(v.Value)
+			out.WriteString(": ")
+			out.WriteString(DebugStr(v.Value))
 			for _, a := range v.Attrs {
-				out += " "
-				out += DebugStr(a)
+				out.WriteString(" ")
+				out.WriteString(DebugStr(a))
 			}
 		}
-		return out
+		return out.String()
 
 	case *ast.Attribute:
 		return v.Text
@@ -578,12 +579,12 @@ func DebugStr(x interface{}) (out string) {
 		if len(v) == 0 {
 			return ""
 		}
-		out := ""
+		var out strings.Builder
 		for _, c := range v {
-			out += DebugStr(c)
-			out += " "
+			out.WriteString(DebugStr(c))
+			out.WriteString(" ")
 		}
-		return out
+		return out.String()
 
 	case []ast.Expr:
 		if len(v) == 0 {
diff --git a/internal/attrs.go b/internal/attrs.go
index b3d1918ea..5e082d4f6 100644
--- a/internal/attrs.go
+++ b/internal/attrs.go
@@ -273,7 +273,7 @@ func scanAttributeTokens(s *scanner.Scanner, startPos token.Pos, close uint64) (
 
 func tokenMaskStr(m uint64) string {
 	var buf strings.Builder
-	for t := token.Token(0); t < 64; t++ {
+	for t := range token.Token(64) {
 		if (m & (1 << t)) != 0 {
 			if buf.Len() > 0 {
 				buf.WriteByte('|')
diff --git a/internal/core/adt/composite.go b/internal/core/adt/composite.go
index faad9ae94..202633794 100644
--- a/internal/core/adt/composite.go
+++ b/internal/core/adt/composite.go
@@ -126,7 +126,7 @@ func (e *Environment) DerefVertex(ctx *OpContext) *Vertex {
 }
 
 func (e *Environment) up(ctx *OpContext, count int32) *Environment {
-	for i := int32(0); i < count; i++ {
+	for range count {
 		e = e.Up
 		ctx.Assertf(ctx.Pos(), e.DerefVertex(ctx) != nil, "Environment.up encountered a nil vertex")
 	}
diff --git a/internal/core/adt/debug.go b/internal/core/adt/debug.go
index 93fe9cb38..955b3c4d1 100644
--- a/internal/core/adt/debug.go
+++ b/internal/core/adt/debug.go
@@ -491,7 +491,7 @@ func indentOnNewline(w io.Writer, level int) {
 }
 
 func indent(w io.Writer, level int) {
-	for i := 0; i < level; i++ {
+	for range level {
 		io.WriteString(w, "   ")
 	}
 }
diff --git a/internal/core/adt/disjunct2.go b/internal/core/adt/disjunct2.go
index ae5d16a94..86cd83cc8 100644
--- a/internal/core/adt/disjunct2.go
+++ b/internal/core/adt/disjunct2.go
@@ -288,7 +288,7 @@ func (n *nodeContext) processDisjunctions() *Bottom {
 
 	// Slow path for processing all disjunctions. Do not use `range` in case
 	// evaluation adds more disjunctions.
-	for i := 0; i < len(a); i++ {
+	for i := range a {
 		d := &a[i]
 		n.nextDisjunction(i, len(a), d.holeID)
 
diff --git a/internal/core/adt/eval_test.go b/internal/core/adt/eval_test.go
index 041a39f46..0f2bdc822 100644
--- a/internal/core/adt/eval_test.go
+++ b/internal/core/adt/eval_test.go
@@ -261,7 +261,7 @@ func BenchmarkUnifyAPI(b *testing.B) {
 		b.StopTimer()
 		ctx := cuecontext.New()
 		v := ctx.CompileString("")
-		for j := 0; j < 500; j++ {
+		for j := range 500 {
 			if j == 400 {
 				b.StartTimer()
 			}
diff --git a/internal/core/export/toposort.go b/internal/core/export/toposort.go
index e3d365862..1660e0ea4 100644
--- a/internal/core/export/toposort.go
+++ b/internal/core/export/toposort.go
@@ -53,7 +53,7 @@ func extractFeatures(in []adt.StructInfo) (a [][]adt.Feature) {
 		if len(sorted) > 0 {
 			occurrences := 1 + s.Repeats
 			// Add this front (1 + Repeats) times to give it proper weight
-			for i := 0; i < occurrences; i++ {
+			for range occurrences {
 				a = append(a, sorted)
 			}
 		}
diff --git a/internal/golangorgx/gopls/lsprpc/autostart_posix.go b/internal/golangorgx/gopls/lsprpc/autostart_posix.go
index 57ccba958..255889c5e 100644
--- a/internal/golangorgx/gopls/lsprpc/autostart_posix.go
+++ b/internal/golangorgx/gopls/lsprpc/autostart_posix.go
@@ -3,7 +3,6 @@
 // license that can be found in the LICENSE file.
 
 //go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
 
 package lsprpc
 
diff --git a/internal/golangorgx/gopls/lsprpc/dialer.go b/internal/golangorgx/gopls/lsprpc/dialer.go
index 977242f0b..0a7c862d1 100644
--- a/internal/golangorgx/gopls/lsprpc/dialer.go
+++ b/internal/golangorgx/gopls/lsprpc/dialer.go
@@ -97,7 +97,7 @@ func (d *autoDialer) dialNet(ctx context.Context) (net.Conn, error) {
 	const retries = 5
 	// It can take some time for the newly started server to bind to our address,
 	// so we retry for a bit.
-	for retry := 0; retry < retries; retry++ {
+	for retry := range retries {
 		startDial := time.Now()
 		netConn, err = net.DialTimeout(d.network, d.addr, dialTimeout)
 		if err == nil {
diff --git a/internal/golangorgx/gopls/protocol/semantic.go b/internal/golangorgx/gopls/protocol/semantic.go
index 65253d032..c393e32f7 100644
--- a/internal/golangorgx/gopls/protocol/semantic.go
+++ b/internal/golangorgx/gopls/protocol/semantic.go
@@ -33,7 +33,7 @@ func SemType(n int) string {
 func SemMods(n int) []string {
 	tokMods := SemanticModifiers()
 	mods := []string{}
-	for i := 0; i < len(tokMods); i++ {
+	for i := range tokMods {
 		if (n & (1 << uint(i))) != 0 {
 			mods = append(mods, tokMods[i])
 		}
diff --git a/internal/golangorgx/gopls/protocol/semtok/semtok.go b/internal/golangorgx/gopls/protocol/semtok/semtok.go
index e69ec825f..026627bb7 100644
--- a/internal/golangorgx/gopls/protocol/semtok/semtok.go
+++ b/internal/golangorgx/gopls/protocol/semtok/semtok.go
@@ -65,7 +65,7 @@ func Encode(
 	x := make([]uint32, 5*len(tokens))
 	var j int
 	var last Token
-	for i := 0; i < len(tokens); i++ {
+	for i := range tokens {
 		item := tokens[i]
 		typ, ok := typeMap[item.Type]
 		if !ok {
diff --git a/internal/golangorgx/gopls/settings/settings.go b/internal/golangorgx/gopls/settings/settings.go
index 6650749a4..50752d757 100644
--- a/internal/golangorgx/gopls/settings/settings.go
+++ b/internal/golangorgx/gopls/settings/settings.go
@@ -7,6 +7,7 @@ package settings
 import (
 	"context"
 	"fmt"
+	"maps"
 	"path/filepath"
 	"regexp"
 	"runtime"
@@ -709,9 +710,7 @@ func (o *Options) Clone() *Options {
 	// and UserOptions can be modified.
 	copyStringMap := func(src map[string]bool) map[string]bool {
 		dst := make(map[string]bool)
-		for k, v := range src {
-			dst[k] = v
-		}
+		maps.Copy(dst, src)
 		return dst
 	}
 	result.Analyses = copyStringMap(o.Analyses)
@@ -729,9 +728,7 @@ func (o *Options) Clone() *Options {
 
 	copyAnalyzerMap := func(src map[string]*Analyzer) map[string]*Analyzer {
 		dst := make(map[string]*Analyzer)
-		for k, v := range src {
-			dst[k] = v
-		}
+		maps.Copy(dst, src)
 		return dst
 	}
 	result.DefaultAnalyzers = copyAnalyzerMap(o.DefaultAnalyzers)
@@ -921,9 +918,7 @@ func (o *Options) set(name string, value interface{}, seen map[string]struct{})
 			if o.Codelenses == nil {
 				o.Codelenses = make(map[string]bool)
 			}
-			for lens, enabled := range lensOverrides {
-				o.Codelenses[lens] = enabled
-			}
+			maps.Copy(o.Codelenses, lensOverrides)
 		}
 
 	case "staticcheck":
diff --git a/internal/golangorgx/gopls/test/integration/expectation.go b/internal/golangorgx/gopls/test/integration/expectation.go
index 1e01a2a59..1743fcbc9 100644
--- a/internal/golangorgx/gopls/test/integration/expectation.go
+++ b/internal/golangorgx/gopls/test/integration/expectation.go
@@ -6,8 +6,9 @@ package integration
 
 import (
 	"fmt"
+	"maps"
 	"regexp"
-	"sort"
+	"slices"
 	"strings"
 
 	"cuelang.org/go/internal/golangorgx/gopls/protocol"
@@ -200,9 +201,7 @@ func ReadDiagnostics(fileName string, into *protocol.PublishDiagnosticsParams) E
 func ReadAllDiagnostics(into *map[string]*protocol.PublishDiagnosticsParams) Expectation {
 	check := func(s State) Verdict {
 		allDiags := make(map[string]*protocol.PublishDiagnosticsParams)
-		for name, diags := range s.diagnostics {
-			allDiags[name] = diags
-		}
+		maps.Copy(allDiags, s.diagnostics)
 		*into = allDiags
 		return Met
 	}
@@ -311,9 +310,7 @@ func (e *Env) DoneDiagnosingChanges() Expectation {
 	}
 
 	// Sort for stability.
-	sort.Slice(expected, func(i, j int) bool {
-		return expected[i] < expected[j]
-	})
+	slices.Sort(expected)
 
 	var all []Expectation
 	for _, source := range expected {
diff --git a/internal/golangorgx/gopls/test/integration/fake/editor.go b/internal/golangorgx/gopls/test/integration/fake/editor.go
index 337d2d7ea..513960897 100644
--- a/internal/golangorgx/gopls/test/integration/fake/editor.go
+++ b/internal/golangorgx/gopls/test/integration/fake/editor.go
@@ -228,9 +228,7 @@ func (e *Editor) Client() *Client {
 // makeSettings builds the settings map for use in LSP settings RPCs.
 func makeSettings(sandbox *Sandbox, config EditorConfig, scopeURI *protocol.URI) map[string]any {
 	env := make(map[string]string)
-	for k, v := range config.Env {
-		env[k] = v
-	}
+	maps.Copy(env, config.Env)
 	for k, v := range env {
 		v = strings.ReplaceAll(v, "$SANDBOX_WORKDIR", sandbox.Workdir.RootURI().Path())
 		env[k] = v
diff --git a/internal/golangorgx/gopls/test/integration/options.go b/internal/golangorgx/gopls/test/integration/options.go
index 15fdba943..88c6282d8 100644
--- a/internal/golangorgx/gopls/test/integration/options.go
+++ b/internal/golangorgx/gopls/test/integration/options.go
@@ -5,6 +5,8 @@
 package integration
 
 import (
+	"maps"
+
 	"cuelang.org/go/internal/golangorgx/gopls/protocol"
 	"cuelang.org/go/internal/golangorgx/gopls/test/integration/fake"
 	"cuelang.org/go/internal/lsp/cache"
@@ -92,9 +94,7 @@ func (s Settings) set(opts *runConfig) {
 	if opts.editor.Settings == nil {
 		opts.editor.Settings = make(map[string]interface{})
 	}
-	for k, v := range s {
-		opts.editor.Settings[k] = v
-	}
+	maps.Copy(opts.editor.Settings, s)
 }
 
 // WorkspaceFolders configures the workdir-relative workspace folders to send
@@ -156,9 +156,7 @@ func (e EnvVars) set(opts *runConfig) {
 	if opts.editor.Env == nil {
 		opts.editor.Env = make(map[string]string)
 	}
-	for k, v := range e {
-		opts.editor.Env[k] = v
-	}
+	maps.Copy(opts.editor.Env, e)
 }
 
 // MessageResponder configures the editor to respond to
diff --git a/internal/golangorgx/tools/diff/lcs/old.go b/internal/golangorgx/tools/diff/lcs/old.go
index a14ae9119..e3d29cfeb 100644
--- a/internal/golangorgx/tools/diff/lcs/old.go
+++ b/internal/golangorgx/tools/diff/lcs/old.go
@@ -376,10 +376,7 @@ func (e *editGraph) twoDone(df, db int) (int, bool) {
 	if (df+db+e.delta)%2 != 0 {
 		return 0, false // diagonals cannot overlap
 	}
-	kmin := -db + e.delta
-	if -df > kmin {
-		kmin = -df
-	}
+	kmin := max(-df, -db+e.delta)
 	kmax := db + e.delta
 	if df < kmax {
 		kmax = df
diff --git a/internal/golangorgx/tools/diff/lcs/sequence.go b/internal/golangorgx/tools/diff/lcs/sequence.go
index 2d72d2630..811bb216e 100644
--- a/internal/golangorgx/tools/diff/lcs/sequence.go
+++ b/internal/golangorgx/tools/diff/lcs/sequence.go
@@ -103,11 +103,3 @@ func commonSuffixLenString(a, b string) int {
 	}
 	return i
 }
-
-func min(x, y int) int {
-	if x < y {
-		return x
-	} else {
-		return y
-	}
-}
diff --git a/internal/golangorgx/tools/diff/ndiff.go b/internal/golangorgx/tools/diff/ndiff.go
index 7c8fb29e6..bbdde2062 100644
--- a/internal/golangorgx/tools/diff/ndiff.go
+++ b/internal/golangorgx/tools/diff/ndiff.go
@@ -72,7 +72,7 @@ func diffRunes(before, after []rune) []Edit {
 func runes(bytes []byte) []rune {
 	n := utf8.RuneCount(bytes)
 	runes := make([]rune, n)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		r, sz := utf8.DecodeRune(bytes)
 		bytes = bytes[sz:]
 		runes[i] = r
diff --git a/internal/golangorgx/tools/event/export/ocagent/metrics.go b/internal/golangorgx/tools/event/export/ocagent/metrics.go
index 521c6470e..7b29a5541 100644
--- a/internal/golangorgx/tools/event/export/ocagent/metrics.go
+++ b/internal/golangorgx/tools/event/export/ocagent/metrics.go
@@ -104,7 +104,7 @@ func dataToTimeseries(data metric.Data, start time.Time) []*wire.TimeSeries {
 	startTimestamp := convertTimestamp(start)
 	timeseries := make([]*wire.TimeSeries, 0, numRows)
 
-	for i := 0; i < numRows; i++ {
+	for i := range numRows {
 		timeseries = append(timeseries, &wire.TimeSeries{
 			StartTimestamp: &startTimestamp,
 			// TODO: labels?
@@ -175,7 +175,7 @@ func dataToPoints(data metric.Data, i int) []*wire.Point {
 // supplied counts, count, and sum.
 func distributionToPoints(counts []int64, count int64, sum float64, bucketBounds []float64, end time.Time) []*wire.Point {
 	buckets := make([]*wire.Bucket, len(counts))
-	for i := 0; i < len(counts); i++ {
+	for i := range counts {
 		buckets[i] = &wire.Bucket{
 			Count: counts[i],
 		}
diff --git a/internal/mod/mvs/mvs_test.go b/internal/mod/mvs/mvs_test.go
index f970847b5..e34adefdb 100644
--- a/internal/mod/mvs/mvs_test.go
+++ b/internal/mod/mvs/mvs_test.go
@@ -481,12 +481,12 @@ func Test(t *testing.T) {
 		if strings.HasPrefix(line, "#") || line == "" {
 			continue
 		}
-		i := strings.Index(line, ":")
-		if i < 0 {
+		before, after, ok := strings.Cut(line, ":")
+		if !ok {
 			t.Fatalf("missing colon: %q", line)
 		}
-		key := strings.TrimSpace(line[:i])
-		val := strings.TrimSpace(line[i+1:])
+		key := strings.TrimSpace(before)
+		val := strings.TrimSpace(after)
 		if key == "" {
 			t.Fatalf("missing key: %q", line)
 		}
diff --git a/mod/modconfig/modconfig_test.go b/mod/modconfig/modconfig_test.go
index 99e94151d..e4e579318 100644
--- a/mod/modconfig/modconfig_test.go
+++ b/mod/modconfig/modconfig_test.go
@@ -194,13 +194,13 @@ func TestConcurrentTokenRefresh(t *testing.T) {
 	for i := range registries {
 		reg := &registries[i]
 		reg.mod = fmt.Sprintf("foo.mod%02d", i)
-		fsys, err := txtar.FS(txtar.Parse([]byte(fmt.Sprintf(`
+		fsys, err := txtar.FS(txtar.Parse(fmt.Appendf(nil, `
 -- %s_v0.0.1/cue.mod/module.cue --
 module: "%s@v0"
 language: version: "v0.8.0"
 -- %s_v0.0.1/bar/bar.cue --
 package bar
-`, reg.mod, reg.mod, reg.mod))))
+`, reg.mod, reg.mod, reg.mod)))
 		qt.Assert(t, qt.IsNil(err))
 		mux := http.NewServeMux()
 		r := ocimem.New()
diff --git a/mod/modzip/zip_test.go b/mod/modzip/zip_test.go
index 219360cba..c00dd585f 100644
--- a/mod/modzip/zip_test.go
+++ b/mod/modzip/zip_test.go
@@ -58,11 +58,11 @@ func readTest(file string) (testParams, error) {
 		if line == "" || line[0] == '#' {
 			continue
 		}
-		eq := strings.IndexByte(line, '=')
-		if eq < 0 {
+		before, after, ok := strings.Cut(line, "=")
+		if !ok {
 			return testParams{}, fmt.Errorf("%s:%d: missing = separator", file, n)
 		}
-		key, value := strings.TrimSpace(line[:eq]), strings.TrimSpace(line[eq+1:])
+		key, value := strings.TrimSpace(before), strings.TrimSpace(after)
 		if strings.HasPrefix(value, "\"") {
 			unq, err := strconv.Unquote(value)
 			if err != nil {
diff --git a/pkg/path/path.go b/pkg/path/path.go
index 247dd7b3f..a7cc3dd94 100644
--- a/pkg/path/path.go
+++ b/pkg/path/path.go
@@ -319,7 +319,7 @@ func Rel(basepath, targpath string, os OS) (string, error) {
 		}
 		buf := make([]byte, size)
 		n := copy(buf, "..")
-		for i := 0; i < seps; i++ {
+		for range seps {
 			buf[n] = x.Separator
 			copy(buf[n+1:], "..")
 			n += 3