diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 19e92390..6d7b2cb6 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,7 +10,7 @@ jobs:
   test:
     strategy:
       matrix:
-        go-version: [1.9.x, 1.10.x, 1.11.x, 1.12.x, 1.13.x, 1.14.x, 1.15.x, 1.16.x, 1.17.x, 1.18.x, tip]
+        go-version: [1.16.x, 1.17.x, 1.18.x, tip]
         full-tests: [false]
         include:
           - go-version: 1.19.x
@@ -41,7 +41,7 @@ jobs:
         if: matrix.full-tests
         run: |
           curl -sL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh |
-              sh -s -- -b $HOME/go/bin v1.49.0
+              sh -s -- -b $HOME/go/bin v1.50.0
           echo $PATH
           $HOME/go/bin/golangci-lint run --max-issues-per-linter 0 \
                                          --max-same-issues 0 \
@@ -71,16 +71,6 @@ jobs:
               GO_TEST_RACE_SAFE_FLAGS="$cover_flags-race-safe.out"
           fi
 
-          case ${{ matrix.go-version }} in
-              1.9.x | 1.10.x) # Before go 1.11, go modules are not available
-                  mkdir -p ../src/github.com/maxatome
-                  ln -s $(pwd) ../src/github.com/$GITHUB_REPOSITORY
-                  export GOPATH=$(dirname $(pwd))
-                  cd $GOPATH/src/github.com/$GITHUB_REPOSITORY
-                  go get -t ./...
-                  ;;
-          esac
-
           export GORACE="halt_on_error=1"
           echo "CLASSIC ==========================================="
           go test                  $GO_TEST_FLAGS           ./...
diff --git a/README.md b/README.md
index 6206697d..385c0fe1 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ go-testdeep
 
 **Extremely flexible golang deep comparison, extends the go testing package.**
 
-Currently supports go 1.9 → 1.19.
+Currently supports go 1.16 → 1.19.
 
 - [Latest news](#latest-news)
 - [Synopsis](#synopsis)
diff --git a/helpers/tdsuite/suite.go b/helpers/tdsuite/suite.go
index d777f79c..da6f219a 100644
--- a/helpers/tdsuite/suite.go
+++ b/helpers/tdsuite/suite.go
@@ -24,10 +24,9 @@ var tType = reflect.TypeOf((*td.T)(nil))
 // tests suite, Setup method is called once before any test runs. If
 // Setup returns an error, the tests suite aborts: no tests are run.
 //
-// Starting go1.14, t.Cleanup() can be called in Setup method. It can
-// replace the definition of a [Destroy] method. It can also be used
-// together, in this case cleanup registered functions are called
-// after [Destroy].
+// t.Cleanup() can be called in Setup method. It can replace the
+// definition of a [Destroy] method. It can also be used together, in
+// this case cleanup registered functions are called after [Destroy].
 type Setup interface {
 	Setup(t *td.T) error
 }
@@ -37,10 +36,9 @@ type Setup interface {
 // itself. If PreTest returns an error, the subtest aborts: the test
 // is not run.
 //
-// Starting go1.14, t.Cleanup() can be called in PreTest method. It can
-// replace the definition of a [PostTest] method. It can also be used
-// together, in this case cleanup registered functions are called
-// after [PostTest].
+// t.Cleanup() can be called in PreTest method. It can replace the
+// definition of a [PostTest] method. It can also be used together, in
+// this case cleanup registered functions are called after [PostTest].
 type PreTest interface {
 	PreTest(t *td.T, testName string) error
 }
diff --git a/helpers/tdsuite/suite_go114_test.go b/helpers/tdsuite/suite_go114_test.go
deleted file mode 100644
index a04fc715..00000000
--- a/helpers/tdsuite/suite_go114_test.go
+++ /dev/null
@@ -1,104 +0,0 @@
-// Copyright (c) 2021, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.14
-// +build go1.14
-
-package tdsuite_test
-
-import (
-	"testing"
-
-	"github.com/maxatome/go-testdeep/helpers/tdsuite"
-	"github.com/maxatome/go-testdeep/td"
-)
-
-// FullCleanup has tests and all possible hooks.
-type FullCleanup struct{ base }
-
-func (f *FullCleanup) Setup(t *td.T) error { f.rec(); return nil }
-func (f *FullCleanup) PreTest(t *td.T, tn string) error {
-	f.rec(tn)
-	t.Cleanup(func() { f.rec(tn) })
-	return nil
-}
-
-func (f *FullCleanup) PostTest(t *td.T, tn string) error {
-	f.rec(tn)
-	t.Cleanup(func() { f.rec(tn) })
-	return nil
-}
-
-func (f *FullCleanup) BetweenTests(t *td.T, prev, next string) error {
-	f.rec(prev, next)
-	return nil
-}
-func (f *FullCleanup) Destroy(t *td.T) error { f.rec(); return nil }
-
-func (f *FullCleanup) Test1(t *td.T) {
-	f.rec()
-	t.Cleanup(func() { f.rec() })
-}
-
-func (f *FullCleanup) Test2(assert *td.T, require *td.T) {
-	f.rec()
-	assert.Cleanup(func() { f.rec() })
-}
-
-func (f *FullCleanup) Test3(t *td.T) {
-	f.rec()
-	t.Cleanup(func() { f.rec() })
-}
-func (f *FullCleanup) Testimony(t *td.T) {} // not a test method
-
-var (
-	_ tdsuite.Setup        = (*FullCleanup)(nil)
-	_ tdsuite.PreTest      = (*FullCleanup)(nil)
-	_ tdsuite.PostTest     = (*FullCleanup)(nil)
-	_ tdsuite.BetweenTests = (*FullCleanup)(nil)
-	_ tdsuite.Destroy      = (*FullCleanup)(nil)
-)
-
-func TestRunCleanup(t *testing.T) {
-	t.Run("Full", func(t *testing.T) {
-		suite := FullCleanup{}
-		td.CmpTrue(t, tdsuite.Run(t, &suite))
-		ok := td.Cmp(t, suite.calls, []string{
-			"Setup",
-			/**/ "PreTest+Test1",
-			/**/ "Test1",
-			/**/ "PostTest+Test1",
-			/**/ "PostTest.Cleanup+Test1",
-			/**/ "Test1.Cleanup",
-			/**/ "PreTest.Cleanup+Test1",
-			"BetweenTests+Test1+Test2",
-			/**/ "PreTest+Test2",
-			/**/ "Test2",
-			/**/ "PostTest+Test2",
-			/**/ "PostTest.Cleanup+Test2",
-			/**/ "Test2.Cleanup",
-			/**/ "PreTest.Cleanup+Test2",
-			"BetweenTests+Test2+Test3",
-			/**/ "PreTest+Test3",
-			/**/ "Test3",
-			/**/ "PostTest+Test3",
-			/**/ "PostTest.Cleanup+Test3",
-			/**/ "Test3.Cleanup",
-			/**/ "PreTest.Cleanup+Test3",
-			"Destroy",
-		})
-		if !ok {
-			for _, c := range suite.calls {
-				switch c[0] {
-				case 'S', 'B', 'D':
-					t.Log(c)
-				default:
-					t.Log("  ", c)
-				}
-			}
-		}
-	})
-}
diff --git a/helpers/tdsuite/suite_test.go b/helpers/tdsuite/suite_test.go
index 93f37c86..df35c885 100644
--- a/helpers/tdsuite/suite_test.go
+++ b/helpers/tdsuite/suite_test.go
@@ -737,3 +737,90 @@ func TestRunErrors(t *testing.T) {
 		})
 	})
 }
+
+// FullCleanup has tests and all possible hooks.
+type FullCleanup struct{ base }
+
+func (f *FullCleanup) Setup(t *td.T) error { f.rec(); return nil }
+func (f *FullCleanup) PreTest(t *td.T, tn string) error {
+	f.rec(tn)
+	t.Cleanup(func() { f.rec(tn) })
+	return nil
+}
+
+func (f *FullCleanup) PostTest(t *td.T, tn string) error {
+	f.rec(tn)
+	t.Cleanup(func() { f.rec(tn) })
+	return nil
+}
+
+func (f *FullCleanup) BetweenTests(t *td.T, prev, next string) error {
+	f.rec(prev, next)
+	return nil
+}
+func (f *FullCleanup) Destroy(t *td.T) error { f.rec(); return nil }
+
+func (f *FullCleanup) Test1(t *td.T) {
+	f.rec()
+	t.Cleanup(func() { f.rec() })
+}
+
+func (f *FullCleanup) Test2(assert *td.T, require *td.T) {
+	f.rec()
+	assert.Cleanup(func() { f.rec() })
+}
+
+func (f *FullCleanup) Test3(t *td.T) {
+	f.rec()
+	t.Cleanup(func() { f.rec() })
+}
+func (f *FullCleanup) Testimony(t *td.T) {} // not a test method
+
+var (
+	_ tdsuite.Setup        = (*FullCleanup)(nil)
+	_ tdsuite.PreTest      = (*FullCleanup)(nil)
+	_ tdsuite.PostTest     = (*FullCleanup)(nil)
+	_ tdsuite.BetweenTests = (*FullCleanup)(nil)
+	_ tdsuite.Destroy      = (*FullCleanup)(nil)
+)
+
+func TestRunCleanup(t *testing.T) {
+	t.Run("Full", func(t *testing.T) {
+		suite := FullCleanup{}
+		td.CmpTrue(t, tdsuite.Run(t, &suite))
+		ok := td.Cmp(t, suite.calls, []string{
+			"Setup",
+			/**/ "PreTest+Test1",
+			/**/ "Test1",
+			/**/ "PostTest+Test1",
+			/**/ "PostTest.Cleanup+Test1",
+			/**/ "Test1.Cleanup",
+			/**/ "PreTest.Cleanup+Test1",
+			"BetweenTests+Test1+Test2",
+			/**/ "PreTest+Test2",
+			/**/ "Test2",
+			/**/ "PostTest+Test2",
+			/**/ "PostTest.Cleanup+Test2",
+			/**/ "Test2.Cleanup",
+			/**/ "PreTest.Cleanup+Test2",
+			"BetweenTests+Test2+Test3",
+			/**/ "PreTest+Test3",
+			/**/ "Test3",
+			/**/ "PostTest+Test3",
+			/**/ "PostTest.Cleanup+Test3",
+			/**/ "Test3.Cleanup",
+			/**/ "PreTest.Cleanup+Test3",
+			"Destroy",
+		})
+		if !ok {
+			for _, c := range suite.calls {
+				switch c[0] {
+				case 'S', 'B', 'D':
+					t.Log(c)
+				default:
+					t.Log("  ", c)
+				}
+			}
+		}
+	})
+}
diff --git a/helpers/tdutil/map.go b/helpers/tdutil/map.go
index fda51dfa..4c7778f5 100644
--- a/helpers/tdutil/map.go
+++ b/helpers/tdutil/map.go
@@ -9,6 +9,8 @@ package tdutil
 import (
 	"reflect"
 	"sort"
+
+	"github.com/maxatome/go-testdeep/internal/visited"
 )
 
 // MapSortedKeys returns a slice of all sorted keys of map m. It
@@ -18,3 +20,72 @@ func MapSortedKeys(m reflect.Value) []reflect.Value {
 	sort.Sort(SortableValues(ks))
 	return ks
 }
+
+type kv struct {
+	key   reflect.Value
+	value reflect.Value
+}
+
+type kvSlice struct {
+	v visited.Visited
+	s []kv
+}
+
+func newKvSlice(l int) *kvSlice {
+	s := kvSlice{}
+	if l > 0 {
+		s.s = make([]kv, 0, l)
+		if l > 1 {
+			s.v = visited.NewVisited()
+		}
+	}
+	return &s
+}
+
+func (s *kvSlice) Len() int { return len(s.s) }
+func (s *kvSlice) Less(i, j int) bool {
+	return cmp(s.v, s.s[i].key, s.s[j].key) < 0
+}
+func (s *kvSlice) Swap(i, j int) { s.s[i], s.s[j] = s.s[j], s.s[i] }
+
+// MapEach calls fn for each key/value pair of map m. If fn
+// returns false, it will not be called again.
+func MapEach(m reflect.Value, fn func(k, v reflect.Value) bool) bool {
+	kvs := newKvSlice(m.Len())
+	iter := m.MapRange()
+	for iter.Next() {
+		kvs.s = append(kvs.s, kv{key: iter.Key(), value: iter.Value()})
+	}
+	sort.Sort(kvs)
+
+	for _, kv := range kvs.s {
+		if !fn(kv.key, kv.value) {
+			return false
+		}
+	}
+	return true
+}
+
+// MapEachValue calls fn for each value of map m. If fn returns
+// false, it will not be called again.
+func MapEachValue(m reflect.Value, fn func(k reflect.Value) bool) bool {
+	iter := m.MapRange()
+	for iter.Next() {
+		if !fn(iter.Value()) {
+			return false
+		}
+	}
+	return true
+}
+
+// MapSortedValues returns a slice of all sorted values of map m. It
+// panics if m's [reflect.Kind] is not [reflect.Map].
+func MapSortedValues(m reflect.Value) []reflect.Value {
+	vs := make([]reflect.Value, 0, m.Len())
+	iter := m.MapRange()
+	for iter.Next() {
+		vs = append(vs, iter.Value())
+	}
+	sort.Sort(SortableValues(vs))
+	return vs
+}
diff --git a/helpers/tdutil/map_go112.go b/helpers/tdutil/map_go112.go
deleted file mode 100644
index e89101d8..00000000
--- a/helpers/tdutil/map_go112.go
+++ /dev/null
@@ -1,86 +0,0 @@
-// Copyright (c) 2018, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.12
-// +build go1.12
-
-package tdutil
-
-import (
-	"reflect"
-	"sort"
-
-	"github.com/maxatome/go-testdeep/internal/visited"
-)
-
-type kv struct {
-	key   reflect.Value
-	value reflect.Value
-}
-
-type kvSlice struct {
-	v visited.Visited
-	s []kv
-}
-
-func newKvSlice(l int) *kvSlice {
-	s := kvSlice{}
-	if l > 0 {
-		s.s = make([]kv, 0, l)
-		if l > 1 {
-			s.v = visited.NewVisited()
-		}
-	}
-	return &s
-}
-
-func (s *kvSlice) Len() int { return len(s.s) }
-func (s *kvSlice) Less(i, j int) bool {
-	return cmp(s.v, s.s[i].key, s.s[j].key) < 0
-}
-func (s *kvSlice) Swap(i, j int) { s.s[i], s.s[j] = s.s[j], s.s[i] }
-
-// MapEach calls fn for each key/value pair of map m. If fn
-// returns false, it will not be called again.
-func MapEach(m reflect.Value, fn func(k, v reflect.Value) bool) bool {
-	kvs := newKvSlice(m.Len())
-	iter := m.MapRange()
-	for iter.Next() {
-		kvs.s = append(kvs.s, kv{key: iter.Key(), value: iter.Value()})
-	}
-	sort.Sort(kvs)
-
-	for _, kv := range kvs.s {
-		if !fn(kv.key, kv.value) {
-			return false
-		}
-	}
-	return true
-}
-
-// MapEachValue calls fn for each value of map m. If fn returns
-// false, it will not be called again.
-func MapEachValue(m reflect.Value, fn func(k reflect.Value) bool) bool {
-	iter := m.MapRange()
-	for iter.Next() {
-		if !fn(iter.Value()) {
-			return false
-		}
-	}
-	return true
-}
-
-// MapSortedValues returns a slice of all sorted values of map m. It
-// panics if m's [reflect.Kind] is not [reflect.Map].
-func MapSortedValues(m reflect.Value) []reflect.Value {
-	vs := make([]reflect.Value, 0, m.Len())
-	iter := m.MapRange()
-	for iter.Next() {
-		vs = append(vs, iter.Value())
-	}
-	sort.Sort(SortableValues(vs))
-	return vs
-}
diff --git a/helpers/tdutil/map_other.go b/helpers/tdutil/map_other.go
deleted file mode 100644
index a8459424..00000000
--- a/helpers/tdutil/map_other.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright (c) 2018, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build !go1.12
-// +build !go1.12
-
-package tdutil
-
-import (
-	"reflect"
-	"sort"
-)
-
-// MapEach calls fn for each key/value pair of map m. If fn
-// returns false, it will not be called again.
-func MapEach(m reflect.Value, fn func(k, v reflect.Value) bool) bool {
-	ks := MapSortedKeys(m)
-	for _, vkey := range ks {
-		if !fn(vkey, m.MapIndex(vkey)) {
-			return false
-		}
-	}
-	return true
-}
-
-// MapEachValue calls fn for each value of map m. If fn returns
-// false, it will not be called again.
-func MapEachValue(m reflect.Value, fn func(k reflect.Value) bool) bool {
-	for _, vkey := range m.MapKeys() {
-		if !fn(m.MapIndex(vkey)) {
-			return false
-		}
-	}
-	return true
-}
-
-// MapSortedValues returns a slice of all sorted values of map m. It
-// panics if m's [reflect.Kind] is not [reflect.Map].
-func MapSortedValues(m reflect.Value) []reflect.Value {
-	vs := make([]reflect.Value, 0, m.Len())
-	for _, vkey := range m.MapKeys() {
-		vs = append(vs, m.MapIndex(vkey))
-	}
-	sort.Sort(SortableValues(vs))
-	return vs
-}
diff --git a/helpers/tdutil/map_go112_test.go b/helpers/tdutil/map_private_test.go
similarity index 97%
rename from helpers/tdutil/map_go112_test.go
rename to helpers/tdutil/map_private_test.go
index c131fbf0..983a4b69 100644
--- a/helpers/tdutil/map_go112_test.go
+++ b/helpers/tdutil/map_private_test.go
@@ -4,9 +4,6 @@
 // This source code is licensed under the BSD-style license found in the
 // LICENSE file in the root directory of this source tree.
 
-//go:build go1.12
-// +build go1.12
-
 package tdutil
 
 import (
diff --git a/helpers/tdutil/name.go b/helpers/tdutil/name.go
index 210eaa8c..7e6fc777 100644
--- a/helpers/tdutil/name.go
+++ b/helpers/tdutil/name.go
@@ -7,7 +7,6 @@
 package tdutil
 
 import (
-	"bytes"
 	"fmt"
 	"io"
 	"strings"
@@ -22,7 +21,7 @@ func BuildTestName(args ...any) string {
 		return ""
 	}
 
-	var b bytes.Buffer
+	var b strings.Builder
 	FbuildTestName(&b, args...)
 	return b.String()
 }
diff --git a/internal/ctxerr/op_error.go b/internal/ctxerr/op_error.go
index 31e92884..ea674d64 100644
--- a/internal/ctxerr/op_error.go
+++ b/internal/ctxerr/op_error.go
@@ -7,9 +7,9 @@
 package ctxerr
 
 import (
-	"bytes"
 	"fmt"
 	"reflect"
+	"strings"
 
 	"github.com/maxatome/go-testdeep/internal/types"
 )
@@ -17,7 +17,7 @@ import (
 // OpBadUsage returns a string to notice the user he passed a bad
 // parameter to an operator constructor.
 func OpBadUsage(op, usage string, param any, pos int, kind bool) *Error {
-	var b bytes.Buffer
+	var b strings.Builder
 	fmt.Fprintf(&b, "usage: %s%s, but received ", op, usage)
 
 	if param == nil {
diff --git a/internal/json/parser_go113_test.go b/internal/json/parser_go113_test.go
deleted file mode 100644
index e7000d16..00000000
--- a/internal/json/parser_go113_test.go
+++ /dev/null
@@ -1,75 +0,0 @@
-// Copyright (c) 2022, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.13
-// +build go1.13
-
-package json_test
-
-import (
-	"testing"
-)
-
-func TestJSON_go113(t *testing.T) {
-	// Extend to golang 1.13 accepted numbers
-
-	// as int64
-	checkJSON(t, `4_2`, `42`)
-	checkJSON(t, `+4_2`, `42`)
-	checkJSON(t, `-4_2`, `-42`)
-
-	checkJSON(t, `0b101010`, `42`)
-	checkJSON(t, `-0b101010`, `-42`)
-	checkJSON(t, `+0b101010`, `42`)
-
-	checkJSON(t, `0b10_1010`, `42`)
-	checkJSON(t, `-0b_10_1010`, `-42`)
-	checkJSON(t, `+0b10_10_10`, `42`)
-
-	checkJSON(t, `0B101010`, `42`)
-	checkJSON(t, `-0B101010`, `-42`)
-	checkJSON(t, `+0B101010`, `42`)
-
-	checkJSON(t, `0B10_1010`, `42`)
-	checkJSON(t, `-0B_10_1010`, `-42`)
-	checkJSON(t, `+0B10_10_10`, `42`)
-
-	checkJSON(t, `0_600`, `384`)
-	checkJSON(t, `-0_600`, `-384`)
-	checkJSON(t, `+0_600`, `384`)
-
-	checkJSON(t, `0o600`, `384`)
-	checkJSON(t, `0o_600`, `384`)
-	checkJSON(t, `-0o600`, `-384`)
-	checkJSON(t, `-0o6_00`, `-384`)
-	checkJSON(t, `+0o600`, `384`)
-	checkJSON(t, `+0o60_0`, `384`)
-
-	checkJSON(t, `0O600`, `384`)
-	checkJSON(t, `0O_600`, `384`)
-	checkJSON(t, `-0O600`, `-384`)
-	checkJSON(t, `-0O6_00`, `-384`)
-	checkJSON(t, `+0O600`, `384`)
-	checkJSON(t, `+0O60_0`, `384`)
-
-	checkJSON(t, `0xBad_Face`, `195951310`)
-	checkJSON(t, `-0x_Bad_Face`, `-195951310`)
-	checkJSON(t, `+0xBad_Face`, `195951310`)
-
-	checkJSON(t, `0XBad_Face`, `195951310`)
-	checkJSON(t, `-0X_Bad_Face`, `-195951310`)
-	checkJSON(t, `+0XBad_Face`, `195951310`)
-
-	// as float64
-	checkJSON(t, `0_600.123`, `600.123`) // float64 can not be an octal number
-	checkJSON(t, `1_5.`, `15`)
-	checkJSON(t, `0.15e+0_2`, `15`)
-	checkJSON(t, `0x1p-2`, `0.25`)
-	checkJSON(t, `0x2.p10`, `2048`)
-	checkJSON(t, `0x1.Fp+0`, `1.9375`)
-	checkJSON(t, `0X.8p-0`, `0.5`)
-	checkJSON(t, `0X_1FFFP-16`, `0.1249847412109375`)
-}
diff --git a/internal/json/parser_test.go b/internal/json/parser_test.go
index 88901e7c..0f85bd82 100644
--- a/internal/json/parser_test.go
+++ b/internal/json/parser_test.go
@@ -128,6 +128,64 @@ func TestJSON(t *testing.T) {
 		checkJSON(t, `0600.`, `600`)        // float64 can not be an octal number
 		checkJSON(t, `.25`, `0.25`)
 		checkJSON(t, `+123.`, `123`)
+
+		// Extend to golang 1.13 accepted numbers
+		// as int64
+		checkJSON(t, `4_2`, `42`)
+		checkJSON(t, `+4_2`, `42`)
+		checkJSON(t, `-4_2`, `-42`)
+
+		checkJSON(t, `0b101010`, `42`)
+		checkJSON(t, `-0b101010`, `-42`)
+		checkJSON(t, `+0b101010`, `42`)
+
+		checkJSON(t, `0b10_1010`, `42`)
+		checkJSON(t, `-0b_10_1010`, `-42`)
+		checkJSON(t, `+0b10_10_10`, `42`)
+
+		checkJSON(t, `0B101010`, `42`)
+		checkJSON(t, `-0B101010`, `-42`)
+		checkJSON(t, `+0B101010`, `42`)
+
+		checkJSON(t, `0B10_1010`, `42`)
+		checkJSON(t, `-0B_10_1010`, `-42`)
+		checkJSON(t, `+0B10_10_10`, `42`)
+
+		checkJSON(t, `0_600`, `384`)
+		checkJSON(t, `-0_600`, `-384`)
+		checkJSON(t, `+0_600`, `384`)
+
+		checkJSON(t, `0o600`, `384`)
+		checkJSON(t, `0o_600`, `384`)
+		checkJSON(t, `-0o600`, `-384`)
+		checkJSON(t, `-0o6_00`, `-384`)
+		checkJSON(t, `+0o600`, `384`)
+		checkJSON(t, `+0o60_0`, `384`)
+
+		checkJSON(t, `0O600`, `384`)
+		checkJSON(t, `0O_600`, `384`)
+		checkJSON(t, `-0O600`, `-384`)
+		checkJSON(t, `-0O6_00`, `-384`)
+		checkJSON(t, `+0O600`, `384`)
+		checkJSON(t, `+0O60_0`, `384`)
+
+		checkJSON(t, `0xBad_Face`, `195951310`)
+		checkJSON(t, `-0x_Bad_Face`, `-195951310`)
+		checkJSON(t, `+0xBad_Face`, `195951310`)
+
+		checkJSON(t, `0XBad_Face`, `195951310`)
+		checkJSON(t, `-0X_Bad_Face`, `-195951310`)
+		checkJSON(t, `+0XBad_Face`, `195951310`)
+
+		// as float64
+		checkJSON(t, `0_600.123`, `600.123`) // float64 can not be an octal number
+		checkJSON(t, `1_5.`, `15`)
+		checkJSON(t, `0.15e+0_2`, `15`)
+		checkJSON(t, `0x1p-2`, `0.25`)
+		checkJSON(t, `0x2.p10`, `2048`)
+		checkJSON(t, `0x1.Fp+0`, `1.9375`)
+		checkJSON(t, `0X.8p-0`, `0.5`)
+		checkJSON(t, `0X_1FFFP-16`, `0.1249847412109375`)
 	})
 
 	t.Run("Special string cases", func(t *testing.T) {
diff --git a/td/cmp_deeply.go b/td/cmp_deeply.go
index b8b35884..9c53bcaf 100644
--- a/td/cmp_deeply.go
+++ b/td/cmp_deeply.go
@@ -147,7 +147,8 @@ func formatError(t TestingT, isFatal bool, err *ctxerr.Error, args ...any) {
 }
 
 func cmpDeeply(ctx ctxerr.Context, t TestingT, got, expected any,
-	args ...any) bool {
+	args ...any,
+) bool {
 	err := deepValueEqualFinal(ctx,
 		reflect.ValueOf(got), reflect.ValueOf(expected))
 	if err == nil {
diff --git a/td/t_anchor.go b/td/t_anchor.go
index 562b7f4c..d2462bba 100644
--- a/td/t_anchor.go
+++ b/td/t_anchor.go
@@ -289,7 +289,7 @@ func (t *T) initAnchors() {
 		// Do not record a finalizer if no name (should not happen
 		// except perhaps in tests)
 		if name != "" {
-			cleanupTB(t.TB, func() {
+			t.Cleanup(func() {
 				allAnchorsMu.Lock()
 				defer allAnchorsMu.Unlock()
 				delete(allAnchors, name)
diff --git a/td/t_anchor_go114.go b/td/t_anchor_go114.go
deleted file mode 100644
index 3eb4db91..00000000
--- a/td/t_anchor_go114.go
+++ /dev/null
@@ -1,16 +0,0 @@
-// Copyright (c) 2020, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.14
-// +build go1.14
-
-package td
-
-import "testing"
-
-func cleanupTB(tb testing.TB, finalize func()) {
-	tb.Cleanup(finalize)
-}
diff --git a/td/t_anchor_other.go b/td/t_anchor_other.go
deleted file mode 100644
index ef83d43f..00000000
--- a/td/t_anchor_other.go
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright (c) 2020, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build !go1.14
-// +build !go1.14
-
-package td
-
-import (
-	"runtime"
-	"testing"
-)
-
-func cleanupTB(tb testing.TB, finalize func()) {
-	runtime.SetFinalizer(tb, func(_ testing.TB) { finalize() })
-}
diff --git a/td/t_struct.go b/td/t_struct.go
index b051cffc..bd9271ca 100644
--- a/td/t_struct.go
+++ b/td/t_struct.go
@@ -7,8 +7,8 @@
 package td
 
 import (
-	"bytes"
 	"reflect"
+	"strings"
 	"sync"
 	"testing"
 
@@ -783,12 +783,12 @@ func (t *T) RunT(name string, f func(t *T)) bool {
 }
 
 func getTrace(args ...any) string {
-	var b bytes.Buffer
+	var b strings.Builder
 	tdutil.FbuildTestName(&b, args...)
 
 	if b.Len() == 0 {
 		b.WriteString("Stack trace:\n")
-	} else if !bytes.HasSuffix(b.Bytes(), []byte{'\n'}) {
+	} else if !strings.HasSuffix(b.String(), "\n") {
 		b.WriteByte('\n')
 	}
 
diff --git a/td/td_map.go b/td/td_map.go
index b590d9ac..0d20d165 100644
--- a/td/td_map.go
+++ b/td/td_map.go
@@ -7,9 +7,9 @@
 package td
 
 import (
-	"bytes"
 	"fmt"
 	"reflect"
+	"strings"
 
 	"github.com/maxatome/go-testdeep/helpers/tdutil"
 	"github.com/maxatome/go-testdeep/internal/ctxerr"
@@ -403,7 +403,7 @@ func (m *tdMap) String() string {
 		return m.stringError()
 	}
 
-	buf := &bytes.Buffer{}
+	var buf strings.Builder
 
 	if m.kind != allMap {
 		buf.WriteString(m.GetLocation().Func)
@@ -418,7 +418,7 @@ func (m *tdMap) String() string {
 		buf.WriteString("{\n")
 
 		for _, entryInfo := range m.expectedEntries {
-			fmt.Fprintf(buf, "  %s: %s,\n", //nolint: errcheck
+			fmt.Fprintf(&buf, "  %s: %s,\n", //nolint: errcheck
 				util.ToString(entryInfo.key),
 				util.ToString(entryInfo.expected))
 		}
diff --git a/td/td_smuggle.go b/td/td_smuggle.go
index 54b03908..9cbd3c18 100644
--- a/td/td_smuggle.go
+++ b/td/td_smuggle.go
@@ -31,9 +31,6 @@ type SmuggledGot struct {
 const smuggled = "<smuggled>"
 
 var (
-	// strconv.ParseComplex only exists from go1.15.
-	parseComplex func(string, int) (complex128, error)
-
 	smuggleFnsMu sync.Mutex
 	smuggleFns   = map[any]reflect.Value{}
 
@@ -76,7 +73,7 @@ type smuggleField struct {
 }
 
 func joinFieldsPath(path []smuggleField) string {
-	var buf bytes.Buffer
+	var buf strings.Builder
 	for i, part := range path {
 		if part.Indexed {
 			fmt.Fprintf(&buf, "[%s]", part.Name)
@@ -220,17 +217,13 @@ func buildFieldsPathFn(path string) (func(any) (smuggleValue, error), error) {
 					}
 					vkey = reflect.ValueOf(f).Convert(tkey)
 				case reflect.Complex64, reflect.Complex128:
-					if parseComplex != nil {
-						c, err := parseComplex(field.Name, 128)
-						if err != nil {
-							return smuggleValue{}, fmt.Errorf(
-								"field %q, %q is not a complex number and so cannot match %s map key type",
-								joinFieldsPath(parts[:idxPart+1]), field.Name, tkey)
-						}
-						vkey = reflect.ValueOf(c).Convert(tkey)
-						break
+					c, err := strconv.ParseComplex(field.Name, 128)
+					if err != nil {
+						return smuggleValue{}, fmt.Errorf(
+							"field %q, %q is not a complex number and so cannot match %s map key type",
+							joinFieldsPath(parts[:idxPart+1]), field.Name, tkey)
 					}
-					fallthrough
+					vkey = reflect.ValueOf(c).Convert(tkey)
 				default:
 					return smuggleValue{}, fmt.Errorf(
 						"field %q, %q cannot match unsupported %s map key type",
@@ -332,12 +325,6 @@ func getCaster(outType reflect.Type) reflect.Value {
 	return fn
 }
 
-// Needed for go≤1.12
-// From go1.13, reflect.ValueOf(&ctxerr.Error{…}) works as expected.
-func errorInterface(err error) reflect.Value {
-	return reflect.ValueOf(&err).Elem()
-}
-
 // buildCaster returns a function:
 //
 //	func(in any) (out outType, err error)
@@ -362,7 +349,7 @@ func buildCaster(outType reflect.Type, useString bool) reflect.Value {
 			if args[0].IsNil() {
 				return []reflect.Value{
 					zeroRet,
-					errorInterface(&ctxerr.Error{
+					reflect.ValueOf(&ctxerr.Error{
 						Message:  "incompatible parameter type",
 						Got:      types.RawString("nil"),
 						Expected: types.RawString(outType.String() + " or convertible or io.Reader"),
@@ -383,11 +370,11 @@ func buildCaster(outType reflect.Type, useString bool) reflect.Value {
 			// Our caller encures Interface() can be called safely
 			switch ta := args[0].Interface().(type) {
 			case io.Reader:
-				var b bytes.Buffer // as we still support go1.9
+				var b bytes.Buffer
 				if _, err := b.ReadFrom(ta); err != nil {
 					return []reflect.Value{
 						zeroRet,
-						errorInterface(&ctxerr.Error{
+						reflect.ValueOf(&ctxerr.Error{
 							Message: "an error occurred while reading from io.Reader",
 							Summary: ctxerr.NewSummary(err.Error()),
 						}),
@@ -407,7 +394,7 @@ func buildCaster(outType reflect.Type, useString bool) reflect.Value {
 			default:
 				return []reflect.Value{
 					zeroRet,
-					errorInterface(&ctxerr.Error{
+					reflect.ValueOf(&ctxerr.Error{
 						Message:  "incompatible parameter type",
 						Got:      types.RawString(args[0].Type().String()),
 						Expected: types.RawString(outType.String() + " or convertible or io.Reader"),
diff --git a/td/td_smuggle_go115.go b/td/td_smuggle_go115.go
deleted file mode 100644
index 1432ffb9..00000000
--- a/td/td_smuggle_go115.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2021, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.15
-// +build go1.15
-
-package td
-
-import "strconv"
-
-// strconv.ParseComplex is only available from go 1.15.
-func init() {
-	parseComplex = strconv.ParseComplex
-}
diff --git a/td/td_smuggle_go115_test.go b/td/td_smuggle_go115_test.go
deleted file mode 100644
index 20dc28ea..00000000
--- a/td/td_smuggle_go115_test.go
+++ /dev/null
@@ -1,35 +0,0 @@
-// Copyright (c) 2021, Maxime Soulé
-// All rights reserved.
-//
-// This source code is licensed under the BSD-style license found in the
-// LICENSE file in the root directory of this source tree.
-
-//go:build go1.15
-// +build go1.15
-
-package td_test
-
-import (
-	"fmt"
-	"testing"
-
-	"github.com/maxatome/go-testdeep/td"
-)
-
-func TestSmuggleFieldsPath_go115(t *testing.T) {
-	type C struct {
-		Iface any
-	}
-
-	got := C{
-		Iface: []any{
-			map[complex64]any{complex(42, 0): []string{"pipo"}},
-			map[complex128]any{complex(42, 0): []string{"pipo"}},
-		},
-	}
-
-	for i := 0; i < 2; i++ {
-		checkOK(t, got, td.Smuggle(fmt.Sprintf("Iface[%d][42][0]", i), "pipo"))
-		checkOK(t, got, td.Smuggle(fmt.Sprintf("Iface[%d][42][0]", i-2), "pipo"))
-	}
-}
diff --git a/td/td_smuggle_private_test.go b/td/td_smuggle_private_test.go
index 4353c62d..d63ea5ce 100644
--- a/td/td_smuggle_private_test.go
+++ b/td/td_smuggle_private_test.go
@@ -128,13 +128,10 @@ func TestBuildFieldsPathFn(t *testing.T) {
 				`field "Iface[str]", "str" is not a float and so cannot match float32 map key type`)
 		}
 
-		// go1.15 min
-		if parseComplex != nil {
-			_, err = fn(Build{Iface: map[complex128]Build{}})
-			if test.Error(t, err) {
-				test.EqualStr(t, err.Error(),
-					`field "Iface[str]", "str" is not a complex number and so cannot match complex128 map key type`)
-			}
+		_, err = fn(Build{Iface: map[complex128]Build{}})
+		if test.Error(t, err) {
+			test.EqualStr(t, err.Error(),
+				`field "Iface[str]", "str" is not a complex number and so cannot match complex128 map key type`)
 		}
 
 		_, err = fn(Build{Iface: map[struct{ A int }]Build{}})
@@ -181,24 +178,4 @@ func TestBuildFieldsPathFn(t *testing.T) {
 		test.EqualStr(t, err.Error(),
 			`it is a int, but a map, array or slice is expected`)
 	}
-
-	// Complex map keys are not supported for go<1.15
-	saveParseComplex := parseComplex
-	defer func() { parseComplex = saveParseComplex }()
-	parseComplex = nil
-
-	fn, err = buildFieldsPathFn("Iface[18].Field")
-	if test.NoError(t, err) {
-		_, err = fn(Build{Iface: map[complex64]Build{}})
-		if test.Error(t, err) {
-			test.EqualStr(t, err.Error(),
-				`field "Iface[18]", "18" cannot match unsupported complex64 map key type`)
-		}
-
-		_, err = fn(Build{Iface: map[complex128]Build{}})
-		if test.Error(t, err) {
-			test.EqualStr(t, err.Error(),
-				`field "Iface[18]", "18" cannot match unsupported complex128 map key type`)
-		}
-	}
 }
diff --git a/td/td_smuggle_test.go b/td/td_smuggle_test.go
index 21843ca0..587ba515 100644
--- a/td/td_smuggle_test.go
+++ b/td/td_smuggle_test.go
@@ -727,6 +727,23 @@ func TestSmuggleFieldsPath(t *testing.T) {
 
 	checkOK(t, x, td.Lax(td.Smuggle("PppA", nil)))
 	checkOK(t, x, td.Smuggle("PppA", td.Nil()))
+
+	//
+	type D struct {
+		Iface any
+	}
+
+	got := D{
+		Iface: []any{
+			map[complex64]any{complex(42, 0): []string{"pipo"}},
+			map[complex128]any{complex(42, 0): []string{"pipo"}},
+		},
+	}
+
+	for i := 0; i < 2; i++ {
+		checkOK(t, got, td.Smuggle(fmt.Sprintf("Iface[%d][42][0]", i), "pipo"))
+		checkOK(t, got, td.Smuggle(fmt.Sprintf("Iface[%d][42][0]", i-2), "pipo"))
+	}
 }
 
 func TestSmuggleTypeBehind(t *testing.T) {
diff --git a/td/types_test.go b/td/types_test.go
index 0a3e5e6f..bb682555 100644
--- a/td/types_test.go
+++ b/td/types_test.go
@@ -4,11 +4,6 @@
 // This source code is licensed under the BSD-style license found in the
 // LICENSE file in the root directory of this source tree.
 
-// Work around https://github.com/golang/go/issues/26995 issue
-// (corrected in go 1.12).
-//go:build go1.12
-// +build go1.12
-
 package td_test
 
 import (