diff --git a/taildrop/taildrop.go b/taildrop/taildrop.go
index 39ab5aff5..c9717c2d4 100644
--- a/taildrop/taildrop.go
+++ b/taildrop/taildrop.go
@@ -169,7 +169,7 @@ func validFilenameRune(r rune) bool {
 		// sent.
 		return false
 	}
-	return unicode.IsPrint(r)
+	return unicode.IsGraphic(r)
 }
 
 func isPartialOrDeleted(s string) bool {
diff --git a/taildrop/taildrop_test.go b/taildrop/taildrop_test.go
index 967fc9b04..df4783c30 100644
--- a/taildrop/taildrop_test.go
+++ b/taildrop/taildrop_test.go
@@ -55,6 +55,7 @@ func TestNextFilename(t *testing.T) {
 		{"my song.mp3", "my song (1).mp3", "my song (2).mp3"},
 		{"archive.7z", "archive (1).7z", "archive (2).7z"},
 		{"foo/bar/fizz", "foo/bar/fizz (1)", "foo/bar/fizz (2)"},
+		{"新完全マスター　N2　文法.pdf", "新完全マスター　N2　文法 (1).pdf", "新完全マスター　N2　文法 (2).pdf"},
 	}
 
 	for _, tt := range tests {