diff --git a/ChangeLog.d/fix-print-non-ascii-string-in-mbedtls_x509_dn_gets.txt b/ChangeLog.d/fix-print-non-ascii-string-in-mbedtls_x509_dn_gets.txt
new file mode 100644
index 0000000..320b0b8
--- /dev/null
+++ b/ChangeLog.d/fix-print-non-ascii-string-in-mbedtls_x509_dn_gets.txt
@@ -0,0 +1,3 @@
+Changes
+   * Fix mbedtls_x509_dn_gets to escape non-ASCII characters as "?". 
+     Contributed by Koh M. Nakagawa in #3326.
diff --git a/library/x509.c b/library/x509.c
index 4c2f721..e969b8d 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -787,7 +787,7 @@
                 break;
 
             c = name->val.p[i];
-            if( c < 32 || c == 127 || ( c > 128 && c < 160 ) )
+            if( c < 32 || c >= 127 )
                  s[i] = '?';
             else s[i] = c;
         }
diff --git a/tests/data_files/non-ascii-string-in-issuer.crt b/tests/data_files/non-ascii-string-in-issuer.crt
new file mode 100644
index 0000000..99db871
--- /dev/null
+++ b/tests/data_files/non-ascii-string-in-issuer.crt
@@ -0,0 +1,22 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 23a9932..831e0ab 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -174,6 +174,10 @@
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA1_C
 x509_cert_info:"data_files/bitstring-in-dn.pem":"cert. version     \: 3\nserial number     \: 02\nissuer name       \: CN=Test CA 01, ST=Ecnivorp, C=XX, emailAddress=tca@example.com, O=Test CA Authority\nsubject name      \: C=XX, O=tca, ST=Ecnivorp, OU=TCA, CN=Client, emailAddress=client@example.com, serialNumber=7101012255, uniqueIdentifier=?7101012255\nissued  on        \: 2015-03-11 12\:06\:51\nexpires on        \: 2025-03-08 12\:06\:51\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nbasic constraints \: CA=false\nsubject alt name  \:\n    <unsupported>\next key usage     \: TLS Web Client Authentication\n"
 
+X509 CRT information Non-ASCII string in issuer name and subject name
+depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_SHA256_C
+x509_cert_info:"data_files/non-ascii-string-in-issuer.crt":"cert. version     \: 3\nserial number     \: 05\:E6\:53\:E7\:1B\:74\:F0\:B5\:D3\:84\:6D\:0C\:6D\:DC\:FA\:3F\:A4\:5A\:2B\:E0\nissuer name       \: C=JP, ST=Tokyo, O=?????????????????? Ltd, CN=?????????????????? CA\nsubject name      \: C=JP, ST=Tokyo, O=?????????????????? Ltd, CN=?????????????????? CA\nissued  on        \: 2020-05-20 16\:17\:23\nexpires on        \: 2020-06-19 16\:17\:23\nsigned using      \: RSA with SHA-256\nRSA key size      \: 2048 bits\nbasic constraints \: CA=true\n"
+
 X509 certificate v1 with extension
 depends_on:MBEDTLS_PEM_PARSE_C:MBEDTLS_RSA_C:MBEDTLS_X509_ALLOW_EXTENSIONS_NON_V3:MBEDTLS_SHA1_C
 x509_cert_info:"data_files/cert_v1_with_ext.crt":"cert. version     \: 1\nserial number     \: BD\:ED\:44\:C7\:D2\:3E\:C2\:A4\nissuer name       \: C=XX, ST=XX, L=XX, O=XX, OU=XX, emailAddress=admin@identity-check.org, CN=identity-check.org\nsubject name      \: C=XX, ST=XX, L=XX, O=XX, OU=XX, emailAddress=admin@identity-check.org, CN=identity-check.org\nissued  on        \: 2013-07-04 16\:17\:02\nexpires on        \: 2014-07-04 16\:17\:02\nsigned using      \: RSA with SHA1\nRSA key size      \: 2048 bits\nsubject alt name  \:\n    dNSName \: identity-check.org\n    dNSName \: www.identity-check.org\n    <unsupported>\n"