diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index d32b43f..38ed038 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -1006,49 +1006,49 @@
 	$(OPENSSL) pkey -pubin -in $< -out $@ -outform DER
 all_final += server1.pubkey.der
 
-rsa4096_pub.pem.der: rsa4096_pub.pem
+rsa4096_pub.der: rsa4096_pub.pem
 	$(OPENSSL) pkey -pubin -in $< -out $@ -outform DER
-all_final += rsa4096_pub.pem.der
+all_final += rsa4096_pub.der
 
-ec_pub.pem.der: ec_pub.pem
+ec_pub.der: ec_pub.pem
 	$(OPENSSL) pkey -pubin -in $< -out $@ -outform DER
-all_final += ec_pub.pem.der
+all_final += ec_pub.der
 
-ec_521_pub.pem.der: ec_521_pub.pem
+ec_521_pub.der: ec_521_pub.pem
 	$(OPENSSL) pkey -pubin -in $< -out $@ -outform DER
-all_final += ec_521_pub.pem.der
+all_final += ec_521_pub.der
 
-ec_bp512_pub.pem.der: ec_bp512_pub.pem
+ec_bp512_pub.der: ec_bp512_pub.pem
 	$(OPENSSL) pkey -pubin -in $< -out $@ -outform DER
-all_final += ec_bp512_pub.pem.der
+all_final += ec_bp512_pub.der
 
 server1.key.der: server1.key
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
 all_final += server1.key.der
 
-rsa4096_prv.pem.der: rsa4096_prv.pem
+rsa4096_prv.der: rsa4096_prv.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += rsa4096_prv.pem.der
+all_final += rsa4096_prv.der
 
-ec_prv.sec1.pem.der: ec_prv.sec1.pem
+ec_prv.sec1.der: ec_prv.sec1.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += ec_prv.sec1.pem.der
+all_final += ec_prv.sec1.der
 
-ec_256_long_prv.pem.der: ec_256_long_prv.pem
+ec_256_long_prv.der: ec_256_long_prv.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += ec_256_long_prv.pem.der
+all_final += ec_256_long_prv.der
 
-ec_521_prv.pem.der: ec_521_prv.pem
+ec_521_prv.der: ec_521_prv.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += ec_521_prv.pem.der
+all_final += ec_521_prv.der
 
-ec_521_short_prv.pem.der: ec_521_short_prv.pem
+ec_521_short_prv.der: ec_521_short_prv.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += ec_521_short_prv.pem.der
+all_final += ec_521_short_prv.der
 
-ec_bp512_prv.pem.der: ec_bp512_prv.pem
+ec_bp512_prv.der: ec_bp512_prv.pem
 	$(OPENSSL) pkey -in $< -out $@ -outform DER
-all_final += ec_bp512_prv.pem.der
+all_final += ec_bp512_prv.der
 
 ################################################################
 ### Generate CSRs for X.509 write test suite
diff --git a/tests/data_files/ec_256_long_prv.pem.der b/tests/data_files/ec_256_long_prv.der
similarity index 100%
rename from tests/data_files/ec_256_long_prv.pem.der
rename to tests/data_files/ec_256_long_prv.der
Binary files differ
diff --git a/tests/data_files/ec_521_prv.pem.der b/tests/data_files/ec_521_prv.der
similarity index 100%
rename from tests/data_files/ec_521_prv.pem.der
rename to tests/data_files/ec_521_prv.der
Binary files differ
diff --git a/tests/data_files/ec_521_pub.pem.der b/tests/data_files/ec_521_pub.der
similarity index 100%
rename from tests/data_files/ec_521_pub.pem.der
rename to tests/data_files/ec_521_pub.der
Binary files differ
diff --git a/tests/data_files/ec_521_short_prv.pem.der b/tests/data_files/ec_521_short_prv.der
similarity index 100%
rename from tests/data_files/ec_521_short_prv.pem.der
rename to tests/data_files/ec_521_short_prv.der
Binary files differ
diff --git a/tests/data_files/ec_bp512_prv.pem.der b/tests/data_files/ec_bp512_prv.der
similarity index 100%
rename from tests/data_files/ec_bp512_prv.pem.der
rename to tests/data_files/ec_bp512_prv.der
Binary files differ
diff --git a/tests/data_files/ec_bp512_pub.pem.der b/tests/data_files/ec_bp512_pub.der
similarity index 100%
rename from tests/data_files/ec_bp512_pub.pem.der
rename to tests/data_files/ec_bp512_pub.der
Binary files differ
diff --git a/tests/data_files/ec_prv.sec1.pem.der b/tests/data_files/ec_prv.sec1.pem.der
deleted file mode 100644
index fe336b7..0000000
--- a/tests/data_files/ec_prv.sec1.pem.der
+++ /dev/null
Binary files differ
diff --git a/tests/data_files/ec_pub.pem.der b/tests/data_files/ec_pub.pem.der
deleted file mode 100644
index 74c5951..0000000
--- a/tests/data_files/ec_pub.pem.der
+++ /dev/null
Binary files differ
diff --git a/tests/data_files/rsa4096_prv.pem.der b/tests/data_files/rsa4096_prv.der
similarity index 100%
rename from tests/data_files/rsa4096_prv.pem.der
rename to tests/data_files/rsa4096_prv.der
Binary files differ
diff --git a/tests/data_files/rsa4096_pub.pem.der b/tests/data_files/rsa4096_pub.der
similarity index 100%
rename from tests/data_files/rsa4096_pub.pem.der
rename to tests/data_files/rsa4096_pub.der
Binary files differ
diff --git a/tests/suites/test_suite_pkwrite.data b/tests/suites/test_suite_pkwrite.data
index 698c8f5..a339cdb 100644
--- a/tests/suites/test_suite_pkwrite.data
+++ b/tests/suites/test_suite_pkwrite.data
@@ -12,7 +12,7 @@
 
 Public key write check RSA 4096 (DER)
 depends_on:MBEDTLS_RSA_C
-pk_write_pubkey_check:"data_files/rsa4096_pub.pem.der":TEST_DER
+pk_write_pubkey_check:"data_files/rsa4096_pub.der":TEST_DER
 
 Public key write check EC 192 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP192R1_ENABLED
@@ -20,7 +20,7 @@
 
 Public key write check EC 192 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP192R1_ENABLED
-pk_write_pubkey_check:"data_files/ec_pub.pem.der":TEST_DER
+pk_write_pubkey_check:"data_files/ec_pub.der":TEST_DER
 
 Public key write check EC 521 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP521R1_ENABLED
@@ -28,7 +28,7 @@
 
 Public key write check EC 521 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP521R1_ENABLED
-pk_write_pubkey_check:"data_files/ec_521_pub.pem.der":TEST_DER
+pk_write_pubkey_check:"data_files/ec_521_pub.der":TEST_DER
 
 Public key write check EC Brainpool 512 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_BP512R1_ENABLED
@@ -36,7 +36,7 @@
 
 Public key write check EC Brainpool 512 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_BP512R1_ENABLED
-pk_write_pubkey_check:"data_files/ec_bp512_pub.pem.der":TEST_DER
+pk_write_pubkey_check:"data_files/ec_bp512_pub.der":TEST_DER
 
 Private key write check RSA
 depends_on:MBEDTLS_RSA_C:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C
@@ -52,7 +52,7 @@
 
 Private key write check RSA 4096 (DER)
 depends_on:MBEDTLS_RSA_C
-pk_write_key_check:"data_files/rsa4096_prv.pem.der":TEST_DER
+pk_write_key_check:"data_files/rsa4096_prv.der":TEST_DER
 
 Private key write check EC 192 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP192R1_ENABLED
@@ -60,7 +60,7 @@
 
 Private key write check EC 192 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP192R1_ENABLED
-pk_write_key_check:"data_files/ec_prv.sec1.pem.der":TEST_DER
+pk_write_key_check:"data_files/ec_prv.sec1.der":TEST_DER
 
 Private key write check EC 256 bits (top bit set)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED
@@ -68,7 +68,7 @@
 
 Private key write check EC 256 bits (top bit set) (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP256R1_ENABLED
-pk_write_key_check:"data_files/ec_256_long_prv.pem.der":TEST_DER
+pk_write_key_check:"data_files/ec_256_long_prv.der":TEST_DER
 
 Private key write check EC 521 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP521R1_ENABLED
@@ -76,7 +76,7 @@
 
 Private key write check EC 521 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP521R1_ENABLED
-pk_write_key_check:"data_files/ec_521_prv.pem.der":TEST_DER
+pk_write_key_check:"data_files/ec_521_prv.der":TEST_DER
 
 Private key write check EC 521 bits (top byte is 0)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_SECP521R1_ENABLED
@@ -84,7 +84,7 @@
 
 Private key write check EC 521 bits (top byte is 0) (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_SECP521R1_ENABLED
-pk_write_key_check:"data_files/ec_521_short_prv.pem.der":TEST_DER
+pk_write_key_check:"data_files/ec_521_short_prv.der":TEST_DER
 
 Private key write check EC Brainpool 512 bits
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_PEM_PARSE_C:MBEDTLS_PEM_WRITE_C:MBEDTLS_ECP_DP_BP512R1_ENABLED
@@ -92,4 +92,4 @@
 
 Private key write check EC Brainpool 512 bits (DER)
 depends_on:MBEDTLS_ECP_LIGHT:MBEDTLS_ECP_DP_BP512R1_ENABLED
-pk_write_key_check:"data_files/ec_bp512_prv.pem.der":TEST_DER
+pk_write_key_check:"data_files/ec_bp512_prv.der":TEST_DER