diff --git a/flag_bool_with_inverse.go b/flag_bool_with_inverse.go
index d885bbda93..e17b0b41f1 100644
--- a/flag_bool_with_inverse.go
+++ b/flag_bool_with_inverse.go
@@ -146,7 +146,7 @@ func (bif *BoolWithInverseFlag) Set(name, val string) error {
 
 	if slices.Contains(append([]string{bif.Name}, bif.Aliases...), name) {
 		if bif.nset {
-			return fmt.Errorf("cannot set both flags `--%s` and `--%s`", bif.Name, bif.inversePrefix()+bif.Name)
+			return bif.errBothSet()
 		}
 		if err := bif.value.Set(val); err != nil {
 			return err
@@ -154,7 +154,7 @@ func (bif *BoolWithInverseFlag) Set(name, val string) error {
 		bif.pset = true
 	} else {
 		if bif.pset {
-			return fmt.Errorf("cannot set both flags `--%s` and `--%s`", bif.Name, bif.inversePrefix()+bif.Name)
+			return bif.errBothSet()
 		}
 		if err := bif.value.Set("false"); err != nil {
 			return err
@@ -169,6 +169,13 @@ func (bif *BoolWithInverseFlag) Set(name, val string) error {
 	return nil
 }
 
+// errBothSet reports that both the flag and its inverse were set, with the
+// same `-` or `--` prefix the help output uses.
+func (bif *BoolWithInverseFlag) errBothSet() error {
+	inverse := bif.inversePrefix() + bif.Name
+	return fmt.Errorf("cannot set both flags `%s%s` and `%s%s`", prefixFor(bif.Name), bif.Name, prefixFor(inverse), inverse)
+}
+
 func (bif *BoolWithInverseFlag) Names() []string {
 	names := append([]string{bif.Name}, bif.Aliases...)
 
@@ -203,12 +210,8 @@ func (bif *BoolWithInverseFlag) String() string {
 
 	i := strings.Index(out, "\t")
 
-	prefix := "--"
-
 	// single character flags are prefixed with `-` instead of `--`
-	if len(bif.Name) == 1 {
-		prefix = "-"
-	}
+	prefix := prefixFor(bif.Name)
 
 	// Guard against a FlagStringer that returns a string without a tab (e.g.
 	// a custom stringer or the default stringer when the flag does not
@@ -220,11 +223,7 @@ func (bif *BoolWithInverseFlag) String() string {
 
 	var aliasParts []string
 	for _, alias := range bif.Aliases {
-		aPrefix := "--"
-		if len(alias) == 1 {
-			aPrefix = "-"
-		}
-		aliasParts = append(aliasParts, aPrefix+alias)
+		aliasParts = append(aliasParts, prefixFor(alias)+alias)
 	}
 
 	names := fmt.Sprintf("%s[%s]%s", prefix, bif.inversePrefix(), bif.Name)
diff --git a/flag_bool_with_inverse_test.go b/flag_bool_with_inverse_test.go
index 895c33d7ec..8d262ca40e 100644
--- a/flag_bool_with_inverse_test.go
+++ b/flag_bool_with_inverse_test.go
@@ -292,6 +292,34 @@ func TestBoolWithInverseWithPrefix(t *testing.T) {
 	}
 }
 
+func TestBoolWithInverseSingleCharName(t *testing.T) {
+	for _, name := range []string{"e", "ü"} {
+		flagMethod := func() *BoolWithInverseFlag {
+			return &BoolWithInverseFlag{
+				Name: name,
+			}
+		}
+
+		errBothSet := fmt.Errorf("cannot set both flags `-%s` and `--no-%s`", name, name)
+		testCases := []*boolWithInverseTestCase{
+			{
+				args: []string{"-" + name, "--no-" + name},
+				err:  errBothSet,
+			},
+			{
+				args: []string{"--no-" + name, "-" + name},
+				err:  errBothSet,
+			},
+		}
+
+		err := runBoolWithInverseFlagTests(t, flagMethod, testCases)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+	}
+}
+
 func TestBoolWithInverseRequired(t *testing.T) {
 	flagMethod := func() *BoolWithInverseFlag {
 		return &BoolWithInverseFlag{
@@ -367,6 +395,12 @@ func TestBoolWithInverseString(t *testing.T) {
 			required: true,
 			expected: "-[no-]e\t",
 		},
+		{
+			testName: "single-char multibyte flag name",
+			flagName: "ü",
+			required: true,
+			expected: "-[no-]ü\t",
+		},
 		{
 			testName: "multi-char flag name",
 			flagName: "env",
@@ -412,6 +446,13 @@ func TestBoolWithInverseString(t *testing.T) {
 			aliases:  []string{"c"},
 			expected: "--[no-]color, -c\t(default: false)",
 		},
+		{
+			testName: "short multibyte alias",
+			flagName: "color",
+			required: false,
+			aliases:  []string{"ü"},
+			expected: "--[no-]color, -ü\t(default: false)",
+		},
 		{
 			testName: "long alias",
 			flagName: "color",