diff --git a/src/encoding/xml/xml.go b/src/encoding/xml/xml.go
index fb52eec5f4..7d2ff01ee9 100644
--- a/src/encoding/xml/xml.go
+++ b/src/encoding/xml/xml.go
@@ -1140,7 +1140,7 @@ func isInCharacterRange(r rune) (inrange bool) {
 	return r == 0x09 ||
 		r == 0x0A ||
 		r == 0x0D ||
-		r >= 0x20 && r <= 0xDF77 ||
+		r >= 0x20 && r <= 0xD7FF ||
 		r >= 0xE000 && r <= 0xFFFD ||
 		r >= 0x10000 && r <= 0x10FFFF
 }
diff --git a/src/encoding/xml/xml_test.go b/src/encoding/xml/xml_test.go
index 7a3511d583..ee4ffa2420 100644
--- a/src/encoding/xml/xml_test.go
+++ b/src/encoding/xml/xml_test.go
@@ -650,6 +650,20 @@ func TestDisallowedCharacters(t *testing.T) {
 	}
 }
 
+func TestIsInCharacterRange(t *testing.T) {
+	invalid := []rune{
+		utf8.MaxRune + 1,
+		0xD800, // surrogate min
+		0xDFFF, // surrogate max
+		-1,
+	}
+	for _, r := range invalid {
+		if isInCharacterRange(r) {
+			t.Errorf("rune %U considered valid", r)
+		}
+	}
+}
+
 var procInstTests = []struct {
 	input  string
 	expect [2]string