diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index 27f2afa..233a2c7 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -344,6 +344,9 @@
 server5-two-directorynames.crt: server5.key
 	$(OPENSSL) req -x509 -new -subj "/C=UK/O=Mbed TLS/CN=Mbed TLS directoryName SAN" -set_serial 77 -config $(test_ca_config_file) -extensions two_directorynames -days 3650 -sha256 -key server5.key -out $@
 
+server5-second-directoryname-malformed.crt: server5-two-directorynames.crt
+	(head -n1 $<; sed -n '2,12p' $< | base64 --decode | hexdump -ve '1/1 "%.2X"' | sed "s/0355040A0C0A4D414C464F524D5F4D45/1555040A0C0A4D414C464F524D5F4D45/" | xxd -r -p | base64 -w64; tail -n1 $<) > $@
+
 all_final += server5-tricky-ip-san.crt
 
 rsa_single_san_uri.crt.der: rsa_single_san_uri.key
diff --git a/tests/data_files/server5-second-directoryname-malformed.crt b/tests/data_files/server5-second-directoryname-malformed.crt
new file mode 100644
index 0000000..11d439b
--- /dev/null
+++ b/tests/data_files/server5-second-directoryname-malformed.crt
@@ -0,0 +1,13 @@
+-----BEGIN CERTIFICATE-----
+MIICCTCCAa+gAwIBAgIBTTAKBggqhkjOPQQDAjBFMQswCQYDVQQGEwJVSzERMA8G
+A1UECgwITWJlZCBUTFMxIzAhBgNVBAMMGk1iZWQgVExTIGRpcmVjdG9yeU5hbWUg
+U0FOMB4XDTIzMDExMjEwMzQxMVoXDTMzMDEwOTEwMzQxMVowRTELMAkGA1UEBhMC
+VUsxETAPBgNVBAoMCE1iZWQgVExTMSMwIQYDVQQDDBpNYmVkIFRMUyBkaXJlY3Rv
+cnlOYW1lIFNBTjBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABDfMVtl2CR5acj7H
+WS3/IG7ufPkGkXTQrRS192giWWKSTuUA2CMR/+ov0jRdXRa9iojCa3cNVc2KKg76
+Aci07f+jgY8wgYwwawYDVR0RBGQwYqRHMEUxCzAJBgNVBAYTAlVLMREwDwYDVQQK
+DAhNYmVkIFRMUzEjMCEGA1UEAwwaTWJlZCBUTFMgZGlyZWN0b3J5TmFtZSBTQU6k
+FzAVMRMwEQYVVQQKDApNQUxGT1JNX01FMB0GA1UdDgQWBBRQYaWP1AfZ14IBDOVl
+f4xjRqcTvjAKBggqhkjOPQQDAgNIADBFAiAHI/ousygMhcDhAb+bK402vAh4+bGK
+UuwPMpd1XQ2FHAIhAL0uuCTzI72PJLyxB4cFtbmodUejDc+Oa02AUW4Ed8Uu
+-----END CERTIFICATE-----