diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index 084b0ab..a833984 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -93,13 +93,14 @@
 cli_crt_extensions_file = cli.opensslconf
 
 cli-rsa.csr: $(cli_crt_key_file_rsa)
-	$(OPENSSL) req -new -key $(cli_crt_key_file_rsa) -passin "pass:$(test_ca_pwd_rsa)" -subj "/C=NL/O=PolarSSL/CN=PolarSSL Client 2" -out $@
+	$(MBEDTLS_CERT_REQ) output_file=$@ filename=$< subject_name="C=NL,O=PolarSSL,CN=PolarSSL Client 2" md=SHA1
 all_intermediate += cli-rsa.csr
-cli-rsa-sha1.crt: $(cli_crt_key_file_rsa) test-ca-sha1.crt cli-rsa.csr
-	$(OPENSSL) x509 -req -extfile $(cli_crt_extensions_file) -extensions cli-rsa -CA test-ca-sha1.crt -CAkey $(test_ca_key_file_rsa) -passin "pass:$(test_ca_pwd_rsa)" -set_serial 4 -days 3653 -sha1 -in cli-rsa.csr -out $@
-all_final += cli-rsa-sha1.crt
-cli-rsa-sha256.crt: $(cli_crt_key_file_rsa) test-ca-sha256.crt cli-rsa.csr
-	$(OPENSSL) x509 -req -extfile $(cli_crt_extensions_file) -extensions cli-rsa -CA test-ca-sha256.crt -CAkey $(test_ca_key_file_rsa) -passin "pass:$(test_ca_pwd_rsa)" -set_serial 4 -days 3653 -sha256 -in cli-rsa.csr -out $@
+
+cli-rsa-sha1.crt: cli-rsa.csr
+	$(MBEDTLS_CERT_WRITE) request_file=$< serial=4 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144406 not_after=20210212144406 md=SHA1 version=3 output_file=$@
+
+cli-rsa-sha256.crt: cli-rsa.csr
+	$(MBEDTLS_CERT_WRITE) request_file=$< serial=4 issuer_crt=$(test_ca_crt) issuer_key=$(test_ca_key_file_rsa) issuer_pwd=$(test_ca_pwd_rsa) not_before=20110212144406 not_after=20210212144406 md=SHA256 version=3 output_file=$@
 all_final += cli-rsa-sha256.crt
 
 test_ca_int_rsa1 = test-int-ca.crt