diff --git a/internal/route/rules/on.go b/internal/route/rules/on.go
index 2c427a7..61cc752 100644
--- a/internal/route/rules/on.go
+++ b/internal/route/rules/on.go
@@ -2,6 +2,7 @@ package rules
 
 import (
 	"net/http"
+	"strings"
 
 	"slices"
 
@@ -230,19 +231,80 @@ var checkers = map[string]struct {
 	},
 }
 
+var asciiSpace = [256]uint8{'\t': 1, '\n': 1, '\v': 1, '\f': 1, '\r': 1, ' ': 1}
+var andSeps = [256]uint8{'&': 1, '\n': 1}
+
+func indexAnd(s string) int {
+	for i, c := range s {
+		if andSeps[c] != 0 {
+			return i
+		}
+	}
+	return -1
+}
+
+func countAnd(s string) int {
+	n := 0
+	for _, c := range s {
+		if andSeps[c] != 0 {
+			n++
+		}
+	}
+	return n
+}
+
+// splitAnd splits a string by "&" and "\n" with all spaces removed.
+// empty strings are not included in the result.
+func splitAnd(s string) []string {
+	if s == "" {
+		return []string{}
+	}
+	n := countAnd(s)
+	a := make([]string, n+1)
+	i := 0
+	for i < n {
+		end := indexAnd(s)
+		if end == -1 {
+			break
+		}
+		beg := 0
+		// trim leading spaces
+		for beg < end && asciiSpace[s[beg]] != 0 {
+			beg++
+		}
+		// trim trailing spaces
+		next := end + 1
+		for end-1 > beg && asciiSpace[s[end-1]] != 0 {
+			end--
+		}
+		// skip empty segments
+		if end > beg {
+			a[i] = s[beg:end]
+			i++
+		}
+		s = s[next:]
+	}
+	s = strings.TrimSpace(s)
+	if s != "" {
+		a[i] = s
+		i++
+	}
+	return a[:i]
+}
+
 // Parse implements strutils.Parser.
 func (on *RuleOn) Parse(v string) error {
 	on.raw = v
 
-	lines := strutils.SplitLine(v)
-	checkAnd := make(CheckMatchAll, 0, len(lines))
+	rules := splitAnd(v)
+	checkAnd := make(CheckMatchAll, 0, len(rules))
 
 	errs := gperr.NewBuilder("rule.on syntax errors")
-	for i, line := range lines {
-		if line == "" {
+	for i, rule := range rules {
+		if rule == "" {
 			continue
 		}
-		parsed, err := parseOn(line)
+		parsed, err := parseOn(rule)
 		if err != nil {
 			errs.Add(err.Subjectf("line %d", i+1))
 			continue
diff --git a/internal/route/rules/on_test.go b/internal/route/rules/on_test.go
index fb60ffc..9b4d3ee 100644
--- a/internal/route/rules/on_test.go
+++ b/internal/route/rules/on_test.go
@@ -12,6 +12,61 @@ import (
 	"golang.org/x/crypto/bcrypt"
 )
 
+func TestSplitAnd(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  []string
+	}{
+		{
+			name:  "empty",
+			input: "",
+			want:  []string{},
+		},
+		{
+			name:  "single",
+			input: "rule",
+			want:  []string{"rule"},
+		},
+		{
+			name:  "multiple",
+			input: "rule1 & rule2",
+			want:  []string{"rule1", "rule2"},
+		},
+		{
+			name:  "multiple_newline",
+			input: "rule1\n\nrule2",
+			want:  []string{"rule1", "rule2"},
+		},
+		{
+			name:  "multiple_newline_and",
+			input: "rule1\nrule2 & rule3",
+			want:  []string{"rule1", "rule2", "rule3"},
+		},
+		{
+			name:  "empty segment",
+			input: "rule1\n& &rule2& rule3",
+			want:  []string{"rule1", "rule2", "rule3"},
+		},
+		{
+			name:  "double_and",
+			input: "rule1\nrule2 && rule3",
+			want:  []string{"rule1", "rule2", "rule3"},
+		},
+		{
+			name:  "spaces_around",
+			input: " rule1\nrule2 & rule3 ",
+			want:  []string{"rule1", "rule2", "rule3"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := splitAnd(tt.input)
+			ExpectEqual(t, got, tt.want)
+		})
+	}
+}
+
 func TestParseOn(t *testing.T) {
 	tests := []struct {
 		name    string