diff --git a/pkg/edit/completion_test.go b/pkg/edit/completion_test.go
index 245d7c2a..96165846 100644
--- a/pkg/edit/completion_test.go
+++ b/pkg/edit/completion_test.go
@@ -7,7 +7,6 @@ import (
 	"github.com/elves/elvish/pkg/eval"
 	. "github.com/elves/elvish/pkg/eval/evaltest"
 	"github.com/elves/elvish/pkg/eval/vals"
-	"github.com/elves/elvish/pkg/prog"
 	"github.com/elves/elvish/pkg/testutil"
 )
 
@@ -63,9 +62,6 @@ func TestCompleteFilename(t *testing.T) {
 }
 
 func TestComplexCandidate(t *testing.T) {
-	restore := prog.SetShowDeprecations(true)
-	defer restore()
-
 	TestWithSetup(t, func(ev *eval.Evaler) {
 		ev.AddGlobal(eval.NsBuilder{}.AddGoFn("", "cc", complexCandidate).Ns())
 	},
diff --git a/pkg/eval/builtin_special_test.go b/pkg/eval/builtin_special_test.go
index 44889cf4..5126db62 100644
--- a/pkg/eval/builtin_special_test.go
+++ b/pkg/eval/builtin_special_test.go
@@ -273,7 +273,7 @@ func TestUse(t *testing.T) {
 
 // Regression test for #1072
 func TestUse_WarnsAboutDeprecatedFeatures(t *testing.T) {
-	restore := prog.SetShowDeprecations(true)
+	restore := prog.SetDeprecationLevel(15)
 	defer restore()
 	libdir, cleanup := testutil.InTestDir()
 	defer cleanup()
diff --git a/pkg/eval/compile_value.go b/pkg/eval/compile_value.go
index eac141d6..d2714fb2 100644
--- a/pkg/eval/compile_value.go
+++ b/pkg/eval/compile_value.go
@@ -245,9 +245,10 @@ func (op *indexingOp) exec(fm *Frame) ([]interface{}, Exception) {
 				if err != nil {
 					return nil, fm.errorp(op, err)
 				}
+				// Check the legacy low:high slice syntax deprecated since 0.15.
 				deprecation := vals.CheckDeprecatedIndex(v, index)
 				if deprecation != "" {
-					fm.Deprecate(deprecation, diag.NewContext(fm.srcMeta.Name, fm.srcMeta.Code, indexOp))
+					fm.Deprecate(deprecation, indexOp, 15)
 				}
 				newvs = append(newvs, result)
 			}
diff --git a/pkg/eval/eval_test.go b/pkg/eval/eval_test.go
index 5c1218cb..1e6d13d1 100644
--- a/pkg/eval/eval_test.go
+++ b/pkg/eval/eval_test.go
@@ -41,14 +41,14 @@ func TestArgs(t *testing.T) {
 }
 
 func TestEvalTimeDeprecate(t *testing.T) {
-	restore := prog.SetShowDeprecations(true)
+	restore := prog.SetDeprecationLevel(42)
 	defer restore()
 	_, cleanup := testutil.InTestDir()
 	defer cleanup()
 
 	TestWithSetup(t, func(ev *Evaler) {
 		ev.AddGlobal(NsBuilder{}.AddGoFn("", "dep", func(fm *Frame) {
-			fm.Deprecate("deprecated", nil)
+			fm.Deprecate("deprecated", nil, 42)
 		}).Ns())
 	},
 		That("dep").PrintsStderrWith("deprecated"),
@@ -58,7 +58,7 @@ func TestEvalTimeDeprecate(t *testing.T) {
 }
 
 func TestCompileTimeDeprecation(t *testing.T) {
-	restore := prog.SetShowDeprecations(true)
+	restore := prog.SetDeprecationLevel(15)
 	defer restore()
 
 	ev := NewEvaler()
diff --git a/pkg/eval/frame.go b/pkg/eval/frame.go
index 310f3720..b1a29a4f 100644
--- a/pkg/eval/frame.go
+++ b/pkg/eval/frame.go
@@ -209,12 +209,15 @@ func (fm *Frame) errorpf(r diag.Ranger, format string, args ...interface{}) Exce
 
 // Deprecate shows a deprecation message. The message is not shown if the same
 // deprecation message has been shown for the same location before.
-func (fm *Frame) Deprecate(msg string, ctx *diag.Context) {
-	if ctx == nil {
+func (fm *Frame) Deprecate(msg string, r diag.Ranger, minLevel int) {
+	var ctx *diag.Context
+	if r == nil {
 		ctx = fm.traceback.Head
+	} else {
+		ctx = diag.NewContext(fm.srcMeta.Name, fm.srcMeta.Code, r)
 	}
 	dep := deprecation{ctx.Name, ctx.Ranging, msg}
-	if prog.ShowDeprecations && fm.Evaler.registerDeprecation(dep) {
+	if prog.DeprecationLevel >= minLevel && fm.Evaler.registerDeprecation(dep) {
 		err := diag.Error{
 			Type: "deprecation", Message: dep.message, Context: *ctx}
 		fm.ErrorFile().WriteString(err.Show("") + "\n")
diff --git a/pkg/eval/var_ref.go b/pkg/eval/var_ref.go
index cf7cff2e..4d856a92 100644
--- a/pkg/eval/var_ref.go
+++ b/pkg/eval/var_ref.go
@@ -192,6 +192,7 @@ func (cp *compiler) checkDeprecatedBuiltin(name string, r diag.Ranger) {
 		return
 	}
 	msg := ""
+	minLevel := 15
 	switch name {
 	case "-source~":
 		msg = `the "source" command is deprecated; use "eval" instead`
@@ -223,7 +224,7 @@ func (cp *compiler) checkDeprecatedBuiltin(name string, r diag.Ranger) {
 		return
 	}
 	dep := deprecation{cp.srcMeta.Name, r.Range(), msg}
-	if prog.ShowDeprecations && cp.deprecations.register(dep) {
+	if prog.DeprecationLevel >= minLevel && cp.deprecations.register(dep) {
 		err := diag.Error{
 			Type: "deprecation", Message: msg,
 			Context: diag.Context{
diff --git a/pkg/prog/prog.go b/pkg/prog/prog.go
index b7682cb8..0cc0b20e 100644
--- a/pkg/prog/prog.go
+++ b/pkg/prog/prog.go
@@ -20,15 +20,17 @@ import (
 // resembles "elvi".
 const defaultWebPort = 3171
 
-// ShowDeprecations is a global flag that controls whether to show deprecations.
-var ShowDeprecations = false
+// DeprecationLevel is a global flag that controls which deprecations to show.
+// If its value is X, Elvish shows deprecations that should be shown for version
+// 0.X.
+var DeprecationLevel = 14
 
-// SetShowDeprecations sets ShowDeprecations to the given value, and returns a
+// SetDeprecationLevel sets ShowDeprecations to the given value, and returns a
 // function to restore the old value.
-func SetShowDeprecations(b bool) func() {
-	save := ShowDeprecations
-	ShowDeprecations = b
-	return func() { ShowDeprecations = save }
+func SetDeprecationLevel(level int) func() {
+	save := DeprecationLevel
+	DeprecationLevel = level
+	return func() { DeprecationLevel = save }
 }
 
 // Flags keeps command-line flags.
@@ -74,7 +76,7 @@ func newFlagSet(stderr io.Writer, f *Flags) *flag.FlagSet {
 	fs.StringVar(&f.DB, "db", "", "path to the database")
 	fs.StringVar(&f.Sock, "sock", "", "path to the daemon socket")
 
-	fs.BoolVar(&ShowDeprecations, "show-deprecations", ShowDeprecations, "whether to show deprecations")
+	fs.IntVar(&DeprecationLevel, "deprecation-level", DeprecationLevel, "show warnings for all features deprecated as of version 0.X")
 
 	return fs
 }
diff --git a/pkg/prog/prog_test.go b/pkg/prog/prog_test.go
index 23ee08cf..270c4752 100644
--- a/pkg/prog/prog_test.go
+++ b/pkg/prog/prog_test.go
@@ -50,14 +50,14 @@ func TestHelp(t *testing.T) {
 }
 
 func TestShowDeprecations(t *testing.T) {
-	restore := SetShowDeprecations(false)
+	restore := SetDeprecationLevel(0)
 	defer restore()
 	f := Setup()
 	defer f.Cleanup()
 
-	Run(f.Fds(), Elvish("-show-deprecations"), testProgram{shouldRun: true})
-	if !ShowDeprecations {
-		t.Errorf("ShowDeprecations = false, want true")
+	Run(f.Fds(), Elvish("-deprecation-level", "42"), testProgram{shouldRun: true})
+	if DeprecationLevel != 42 {
+		t.Errorf("ShowDeprecations = %d, want 42", DeprecationLevel)
 	}
 }