diff --git a/lib.go b/lib.go
index 424d3f9..31b64a5 100644
--- a/lib.go
+++ b/lib.go
@@ -21,7 +21,6 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
-	"unicode"
 )
 
 // ReadZipReader can be used to read the spreadsheet in memory without touching the
@@ -588,10 +587,6 @@ func bstrUnmarshal(s string) (result string) {
 		subStr := s[match[0]:match[1]]
 		if subStr == "_x005F_" {
 			cursor = match[1]
-			if l > match[1]+6 && !bstrEscapeExp.MatchString(s[match[1]:match[1]+6]) {
-				result += subStr
-				continue
-			}
 			result += "_"
 			continue
 		}
@@ -607,15 +602,7 @@ func bstrUnmarshal(s string) (result string) {
 				result += subStr
 				continue
 			}
-			hasRune := false
-			for _, c := range v {
-				if unicode.IsControl(c) {
-					hasRune = true
-				}
-			}
-			if !hasRune {
-				result += v
-			}
+			result += v
 		}
 	}
 	if cursor < l {
diff --git a/lib_test.go b/lib_test.go
index 025bc85..556ed91 100644
--- a/lib_test.go
+++ b/lib_test.go
@@ -263,21 +263,21 @@ func TestGenXMLNamespace(t *testing.T) {
 func TestBstrUnmarshal(t *testing.T) {
 	bstrs := map[string]string{
 		"*":                           "*",
-		"*_x0000_":                    "*",
-		"*_x0008_":                    "*",
-		"_x0008_*":                    "*",
-		"*_x0008_*":                   "**",
+		"*_x0000_":                    "*\x00",
+		"*_x0008_":                    "*\b",
+		"_x0008_*":                    "\b*",
+		"*_x0008_*":                   "*\b*",
 		"*_x4F60__x597D_":             "*你好",
 		"*_xG000_":                    "*_xG000_",
 		"*_xG05F_x0001_*":             "*_xG05F*",
-		"*_x005F__x0008_*":            "*_x005F_*",
+		"*_x005F__x0008_*":            "*_\b*",
 		"*_x005F_x0001_*":             "*_x0001_*",
-		"*_x005f_x005F__x0008_*":      "*_x005F_*",
+		"*_x005f_x005F__x0008_*":      "*_x005F_\b*",
 		"*_x005F_x005F_xG05F_x0006_*": "*_x005F_xG05F*",
 		"*_x005F_x005F_x005F_x0006_*": "*_x005F_x0006_*",
-		"_x005F__x0008_******":        "_x005F_******",
-		"******_x005F__x0008_":        "******_x005F_",
-		"******_x005F__x0008_******":  "******_x005F_******",
+		"_x005F__x0008_******":        "_\b******",
+		"******_x005F__x0008_":        "******_\b",
+		"******_x005F__x0008_******":  "******_\b******",
 	}
 	for bstr, expected := range bstrs {
 		assert.Equal(t, expected, bstrUnmarshal(bstr))