diff --git a/internal/vm/arith.go b/internal/vm/arith.go
index bfabb142..86b4ea75 100644
--- a/internal/vm/arith.go
+++ b/internal/vm/arith.go
@@ -672,7 +672,7 @@ func (vm *VM) repeatLong(b object.Value) int64 {
 		if v.I.IsInt64() {
 			return v.I.Int64()
 		}
-		raise("RangeError", "bignum too big to convert into `long'")
+		raise("RangeError", "bignum too big to convert into 'long'")
 	case object.Float:
 		f := float64(v)
 		if math.IsNaN(f) {
diff --git a/internal/vm/builtins.go b/internal/vm/builtins.go
index b64e8ec5..d7983b86 100644
--- a/internal/vm/builtins.go
+++ b/internal/vm/builtins.go
@@ -6036,7 +6036,7 @@ func (vm *VM) bootstrap() {
 		if i, ok := self.(object.Integer); ok {
 			return int64(i)
 		}
-		raise("RangeError", "bignum too big to convert into `long'")
+		raise("RangeError", "bignum too big to convert into 'long'")
 		return 0
 	}
 	vm.cInteger.defineArgc("abs", 0, func(_ *VM, self object.Value, _ []object.Value, _ *Proc) object.Value {
@@ -10359,7 +10359,7 @@ func cvarNameArg(v object.Value) string {
 		raise("TypeError", "%s is not a symbol nor a string", v.Inspect())
 	}
 	if !strings.HasPrefix(name, "@@") || len(name) == 2 {
-		raise("NameError", "`%s' is not allowed as a class variable name", name)
+		raise("NameError", "'%s' is not allowed as a class variable name", name)
 	}
 	return name
 }
diff --git a/internal/vm/dir.go b/internal/vm/dir.go
index c0d43cc5..621e60fa 100644
--- a/internal/vm/dir.go
+++ b/internal/vm/dir.go
@@ -500,7 +500,7 @@ func dirHomeStr() string {
 	if h, err := osCurrentUserHome(); err == nil && h != "" {
 		return h
 	}
-	raise("ArgumentError", "couldn't find HOME environment -- expanding `~'")
+	raise("ArgumentError", "couldn't find HOME environment -- expanding '~'")
 	return ""
 }
 
diff --git a/internal/vm/file.go b/internal/vm/file.go
index 23ff1847..80809944 100644
--- a/internal/vm/file.go
+++ b/internal/vm/file.go
@@ -1007,7 +1007,7 @@ func expandTildePath(p string) string {
 	if name == "" { // "~" or "~/..." -> $HOME
 		home := os.Getenv("HOME")
 		if home == "" {
-			raise("ArgumentError", "couldn't find HOME environment -- expanding `~'")
+			raise("ArgumentError", "couldn't find HOME environment -- expanding '~'")
 		}
 		if !isAbsPath(toSlash(home)) {
 			raise("ArgumentError", "non-absolute home")
diff --git a/internal/vm/ivar_reflect.go b/internal/vm/ivar_reflect.go
index e7896845..41bcad66 100644
--- a/internal/vm/ivar_reflect.go
+++ b/internal/vm/ivar_reflect.go
@@ -68,7 +68,7 @@ func (vm *VM) ivarNameArg(arg object.Value) string {
 		}
 	}
 	if !validIvarName(name) {
-		raise("NameError", "`%s' is not allowed as an instance variable name", name)
+		raise("NameError", "'%s' is not allowed as an instance variable name", name)
 	}
 	return name
 }
diff --git a/internal/vm/message_quoting_test.go b/internal/vm/message_quoting_test.go
new file mode 100644
index 00000000..c804f43c
--- /dev/null
+++ b/internal/vm/message_quoting_test.go
@@ -0,0 +1,139 @@
+// Copyright (c) the go-embedded-ruby/ruby authors
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+package vm
+
+import (
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+// oldQuoting is MRI's pre-3.4 form: a backtick, then at least one character
+// that is neither a quote nor another backtick, then an apostrophe.
+var oldQuoting = regexp.MustCompile("`[^`\"'\n]+'")
+
+// doubleQuotedSegments returns the contents of each "..." string on a line.
+//
+// ⛔ It exists because the first version of this gate matched the whole line and
+// reported string_undump.go twice: that message is a Go RAW string, where the
+// backtick is the delimiter and not part of the message at all. A detector that
+// cannot tell a delimiter from content reports defects that are not there.
+func doubleQuotedSegments(line string) []string {
+	var out []string
+	var cur strings.Builder
+	inside, escaped := false, false
+	for _, r := range line {
+		switch {
+		case escaped:
+			cur.WriteRune(r)
+			escaped = false
+		case inside && r == '\\':
+			escaped = true
+		case r == '"':
+			if inside {
+				out = append(out, cur.String())
+				cur.Reset()
+			}
+			inside = !inside
+		case inside:
+			cur.WriteRune(r)
+		}
+	}
+	return out
+}
+
+// ⛔ MRI stopped writing `name' and writes 'name' since 3.4; v4.0.9 is
+// straight-quoted throughout (numeric.c:3207, file.c:3908). rbgo migrated most
+// of its messages and missed thirteen, which was only visible because the SAME
+// message existed in both spellings in this one package:
+//
+//	builtins.go:3321   "bignum too big to convert into 'long'"
+//	arith.go:675       "bignum too big to convert into `long'"
+//
+// A note saying "finish the migration" would be forgotten exactly the way the
+// first half was, so this is a gate instead. It reports the number of files it
+// read: a scan that cannot say what it looked at cannot be told from a scan
+// that could not look.
+func TestErrorMessagesUseStraightQuotesNotTheOldBacktickForm(t *testing.T) {
+	entries, err := os.ReadDir(".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var offenders []string
+	read := 0
+	for _, e := range entries {
+		name := e.Name()
+		if e.IsDir() || !strings.HasSuffix(name, ".go") || strings.HasSuffix(name, "_test.go") {
+			continue
+		}
+		b, err := os.ReadFile(name)
+		if err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+		read++
+		for i, line := range strings.Split(string(b), "\n") {
+			if !strings.Contains(line, "raise(") {
+				continue
+			}
+			for _, seg := range doubleQuotedSegments(line) {
+				if oldQuoting.MatchString(seg) {
+					offenders = append(offenders,
+						filepath.Join("internal/vm", name)+":"+strconv.Itoa(i+1)+"  "+strings.TrimSpace(line))
+					break
+				}
+			}
+		}
+	}
+	// ⛔ The denominator. If a refactor moves these messages out of this package
+	// the scan would find nothing and quietly pass, so assert it read something.
+	if read < 50 {
+		t.Fatalf("only %d source files scanned — the gate is looking in the wrong place", read)
+	}
+	t.Logf("scanned %d non-test source files in internal/vm", read)
+	if len(offenders) > 0 {
+		t.Errorf("%d message(s) still use MRI's pre-3.4 `x' quoting; v4.0.9 writes 'x':\n%s",
+			len(offenders), strings.Join(offenders, "\n"))
+	}
+}
+
+// The judge and its subject must count alike, so the detector is tested on the
+// shapes it has to separate rather than only on the tree as it stands today.
+func TestTheQuotingGateSeparatesAMessageFromADelimiter(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		line string
+		want bool
+	}{
+		{"the old form inside a double-quoted message",
+			"\t\traise(\"NameError\", \"`%s' is not allowed as a class variable name\", name)", true},
+		{"the new form", "\t\traise(\"NameError\", \"'%s' is not allowed as a class variable name\", name)", false},
+		{"a backtick that delimits a Go RAW string is not content",
+			"\t\traise(\"RuntimeError\", `invalid dumped string; not wrapped with '\"' nor '\"...\"' form`)", false},
+		{"prose that pairs its backticks",
+			"\traise(\"NotImplementedError\", \"`%%x`/backtick command execution is not supported on wasm\")", false},
+		{"a line with no raise at all", "\t// see `foo' in the notes", false},
+		{"an escaped quote does not end the segment",
+			"\t\traise(\"ArgumentError\", \"say \\\"`x'\\\" please\")", true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			got := false
+			if strings.Contains(tc.line, "raise(") {
+				for _, seg := range doubleQuotedSegments(tc.line) {
+					if oldQuoting.MatchString(seg) {
+						got = true
+						break
+					}
+				}
+			}
+			if got != tc.want {
+				t.Errorf("flagged=%v want=%v for:\n%s\nsegments: %q",
+					got, tc.want, tc.line, doubleQuotedSegments(tc.line))
+			}
+		})
+	}
+}
diff --git a/internal/vm/module_wave16_internal_test.go b/internal/vm/module_wave16_internal_test.go
index bf902371..fb80f9d5 100644
--- a/internal/vm/module_wave16_internal_test.go
+++ b/internal/vm/module_wave16_internal_test.go
@@ -33,8 +33,12 @@ func TestWave16NameCoercion(t *testing.T) {
 			"can't convert Object to String (Object#to_str gives Integer)"},
 		{"Module.new.const_set(\"x\", 1)", "NameError", "wrong constant name x"},
 		{"Module.new.const_set(\"Name=\", 1)", "NameError", "wrong constant name Name="},
-		{"Class.new.class_variable_get(:foo)", "NameError", "`foo' is not allowed as a class variable name"},
-		{"Class.new.class_variable_get(:@@)", "NameError", "`@@' is not allowed as a class variable name"},
+		// ⛔ These two moved with the quoting, not because they were wrong. MRI
+		// writes 'foo' and not `foo' since 3.4, and v4.0.9 is straight-quoted
+		// throughout (numeric.c:3207, file.c:3908). Measured on 4.0.7:
+		// "'nope' is not allowed as an instance variable name".
+		{"Class.new.class_variable_get(:foo)", "NameError", "'foo' is not allowed as a class variable name"},
+		{"Class.new.class_variable_get(:@@)", "NameError", "'@@' is not allowed as a class variable name"},
 	}
 	for _, c := range errs {
 		if cls, msg := evalErr(t, c.src); cls != c.class || msg != c.msg {
diff --git a/internal/vm/modulefunc.go b/internal/vm/modulefunc.go
index 7d337659..3e062bf6 100644
--- a/internal/vm/modulefunc.go
+++ b/internal/vm/modulefunc.go
@@ -531,7 +531,7 @@ func (vm *VM) coerceConstName(v object.Value) string {
 func (vm *VM) coerceCvarName(v object.Value) string {
 	name := vm.coerceNameArg(v)
 	if len(name) < 3 || name[0] != '@' || name[1] != '@' {
-		raise("NameError", "`%s' is not allowed as a class variable name", name)
+		raise("NameError", "'%s' is not allowed as a class variable name", name)
 	}
 	return name
 }
diff --git a/internal/vm/numeric_edges.go b/internal/vm/numeric_edges.go
index f2431ac7..ba3b1d2c 100644
--- a/internal/vm/numeric_edges.go
+++ b/internal/vm/numeric_edges.go
@@ -46,11 +46,11 @@ func (vm *VM) toRoundInt(a object.Value) int {
 	switch v := a.(type) {
 	case object.Integer:
 		if int64(v) < math.MinInt32 || int64(v) > math.MaxInt32 {
-			raise("RangeError", "integer %d too big to convert to `int'", int64(v))
+			raise("RangeError", "integer %d too big to convert to 'int'", int64(v))
 		}
 		return clampInt(v)
 	case *object.Bignum:
-		raise("RangeError", "bignum too big to convert into `long'")
+		raise("RangeError", "bignum too big to convert into 'long'")
 	case object.Float:
 		f := math.Trunc(float64(v))
 		if math.IsNaN(float64(v)) || math.IsInf(float64(v), 0) || f < math.MinInt32 || f > math.MaxInt32 {
diff --git a/internal/vm/oauth2_client.go b/internal/vm/oauth2_client.go
index 8b50214a..2f5ffcdb 100644
--- a/internal/vm/oauth2_client.go
+++ b/internal/vm/oauth2_client.go
@@ -88,7 +88,7 @@ func (vm *VM) registerOAuth2StrategyMethods(cls *RClass) {
 	cls.define("authorize_url", func(vm *VM, self object.Value, args []object.Value, _ *Proc) object.Value {
 		s := self.(*OAuth2Strategy)
 		if s.grant != "auth_code" {
-			raise("NoMethodError", "undefined method `authorize_url' for %s", s.className)
+			raise("NoMethodError", "undefined method 'authorize_url' for %s", s.className)
 		}
 		return object.NewString(s.client.AuthCode().AuthorizeURL(oauth2Params(args)))
 	})
diff --git a/internal/vm/opentelemetry.go b/internal/vm/opentelemetry.go
index 8a5c6612..fa976f2b 100644
--- a/internal/vm/opentelemetry.go
+++ b/internal/vm/opentelemetry.go
@@ -113,7 +113,7 @@ func (vm *VM) registerOpenTelemetryProvider(cls *RClass) {
 	cls.define("add_span_processor", func(_ *VM, v object.Value, args []object.Value, _ *Proc) object.Value {
 		p := v.(*OTelTracerProvider)
 		if p.sdk == nil {
-			raise("NoMethodError", "undefined method `add_span_processor' for a non-SDK tracer provider")
+			raise("NoMethodError", "undefined method 'add_span_processor' for a non-SDK tracer provider")
 		}
 		if len(args) == 0 {
 			raise("ArgumentError", "wrong number of arguments (given 0, expected 1)")
diff --git a/internal/vm/rspec.go b/internal/vm/rspec.go
index ac8ca23d..9fdbc869 100644
--- a/internal/vm/rspec.go
+++ b/internal/vm/rspec.go
@@ -249,7 +249,7 @@ func (vm *VM) registerRSpecMatcherClass(mod *RClass) {
 	d("of", func(vm *VM, v object.Value, args []object.Value, _ *Proc) object.Value {
 		m := self(v)
 		if m.chain == nil || m.chain.within == nil {
-			raise("NoMethodError", "undefined method `of' for matcher")
+			raise("NoMethodError", "undefined method 'of' for matcher")
 		}
 		return &RSpecMatcher{m: rspec.BeWithin(m.chain.within.delta).Of(rspecFloatArg(args))}
 	})
@@ -257,7 +257,7 @@ func (vm *VM) registerRSpecMatcherClass(mod *RClass) {
 	d("with", func(vm *VM, v object.Value, args []object.Value, _ *Proc) object.Value {
 		m := self(v)
 		if m.chain == nil || m.chain.respTo == nil {
-			raise("NoMethodError", "undefined method `with' for matcher")
+			raise("NoMethodError", "undefined method 'with' for matcher")
 		}
 		n := clampInt(rspecIntArg(args))
 		return &RSpecMatcher{m: rspec.RespondTo(m.chain.respTo.names...).With(n)}