diff --git a/encode_string.go b/encode_string.go
index f9ec629..bd3b140 100644
--- a/encode_string.go
+++ b/encode_string.go
@@ -11,7 +11,7 @@ import (
 // All values are true except for the ASCII control characters (0-31), the
 // double quote ("), the backslash character ("\"), HTML opening and closing
 // tags ("<" and ">"), and the ampersand ("&").
-var htmlSafeSet = [utf8.RuneSelf]bool{
+var htmlSafeSet = [256]bool{
 	' ':      true,
 	'!':      true,
 	'"':      false,
@@ -108,6 +108,134 @@ var htmlSafeSet = [utf8.RuneSelf]bool{
 	'}':      true,
 	'~':      true,
 	'\u007f': true,
+	0x80:     false,
+	0x81:     false,
+	0x82:     false,
+	0x83:     false,
+	0x84:     false,
+	0x85:     false,
+	0x86:     false,
+	0x87:     false,
+	0x88:     false,
+	0x89:     false,
+	0x8a:     false,
+	0x8b:     false,
+	0x8c:     false,
+	0x8d:     false,
+	0x8e:     false,
+	0x8f:     false,
+	0x90:     false,
+	0x91:     false,
+	0x92:     false,
+	0x93:     false,
+	0x94:     false,
+	0x95:     false,
+	0x96:     false,
+	0x97:     false,
+	0x98:     false,
+	0x99:     false,
+	0x9a:     false,
+	0x9b:     false,
+	0x9c:     false,
+	0x9d:     false,
+	0x9e:     false,
+	0x9f:     false,
+	0xa0:     false,
+	0xa1:     false,
+	0xa2:     false,
+	0xa3:     false,
+	0xa4:     false,
+	0xa5:     false,
+	0xa6:     false,
+	0xa7:     false,
+	0xa8:     false,
+	0xa9:     false,
+	0xaa:     false,
+	0xab:     false,
+	0xac:     false,
+	0xad:     false,
+	0xae:     false,
+	0xaf:     false,
+	0xb0:     false,
+	0xb1:     false,
+	0xb2:     false,
+	0xb3:     false,
+	0xb4:     false,
+	0xb5:     false,
+	0xb6:     false,
+	0xb7:     false,
+	0xb8:     false,
+	0xb9:     false,
+	0xba:     false,
+	0xbb:     false,
+	0xbc:     false,
+	0xbd:     false,
+	0xbe:     false,
+	0xbf:     false,
+	0xc0:     false,
+	0xc1:     false,
+	0xc2:     false,
+	0xc3:     false,
+	0xc4:     false,
+	0xc5:     false,
+	0xc6:     false,
+	0xc7:     false,
+	0xc8:     false,
+	0xc9:     false,
+	0xca:     false,
+	0xcb:     false,
+	0xcc:     false,
+	0xcd:     false,
+	0xce:     false,
+	0xcf:     false,
+	0xd0:     false,
+	0xd1:     false,
+	0xd2:     false,
+	0xd3:     false,
+	0xd4:     false,
+	0xd5:     false,
+	0xd6:     false,
+	0xd7:     false,
+	0xd8:     false,
+	0xd9:     false,
+	0xda:     false,
+	0xdb:     false,
+	0xdc:     false,
+	0xdd:     false,
+	0xde:     false,
+	0xdf:     false,
+	0xe0:     false,
+	0xe1:     false,
+	0xe2:     false,
+	0xe3:     false,
+	0xe4:     false,
+	0xe5:     false,
+	0xe6:     false,
+	0xe7:     false,
+	0xe8:     false,
+	0xe9:     false,
+	0xea:     false,
+	0xeb:     false,
+	0xec:     false,
+	0xed:     false,
+	0xee:     false,
+	0xef:     false,
+	0xf0:     false,
+	0xf1:     false,
+	0xf2:     false,
+	0xf3:     false,
+	0xf4:     false,
+	0xf5:     false,
+	0xf6:     false,
+	0xf7:     false,
+	0xf8:     false,
+	0xf9:     false,
+	0xfa:     false,
+	0xfb:     false,
+	0xfc:     false,
+	0xfd:     false,
+	0xfe:     false,
+	0xff:     false,
 }
 
 // safeSet holds the value true if the ASCII character with the given array
@@ -222,8 +350,7 @@ func (e *Encoder) encodeEscapedString(s string) {
 	// write string, the fast path, without utf8 and escape support
 	i := 0
 	for ; i < valLen; i++ {
-		c := s[i]
-		if c >= utf8.RuneSelf || !htmlSafeSet[c] {
+		if !htmlSafeSet[s[i]] {
 			break
 		}
 	}