diff --git a/tests/data_files/Makefile b/tests/data_files/Makefile
index 0af27fe..c0ad9b0 100644
--- a/tests/data_files/Makefile
+++ b/tests/data_files/Makefile
@@ -1089,7 +1089,7 @@
 
 # TLSv1.3 test certificates
 ecdsa_secp256r1.key: ec_256_prv.pem
-	ln -s $< $@
+	cp $< $@
 
 ecdsa_secp256r1.csr: ecdsa_secp256r1.key
 	$(OPENSSL) req -new -subj "/C=NL/O=PolarSSL/CN=localhost" \
@@ -1102,7 +1102,7 @@
 tls13_certs: ecdsa_secp256r1.crt ecdsa_secp256r1.key
 
 ecdsa_secp384r1.key: ec_384_prv.pem
-	ln -s $< $@
+	cp $< $@
 ecdsa_secp384r1.csr: ecdsa_secp384r1.key
 	$(OPENSSL) req -new -subj "/C=NL/O=PolarSSL/CN=localhost" \
 					-key $< -out $@
@@ -1114,7 +1114,7 @@
 tls13_certs: ecdsa_secp384r1.crt ecdsa_secp384r1.key
 
 ecdsa_secp521r1.key: ec_521_prv.pem
-	ln -s $< $@
+	cp $< $@
 ecdsa_secp521r1.csr: ecdsa_secp521r1.key
 	$(OPENSSL) req -new -subj "/C=NL/O=PolarSSL/CN=localhost" \
 					-key $< -out $@
diff --git a/tests/data_files/ecdsa_secp256r1.key b/tests/data_files/ecdsa_secp256r1.key
deleted file mode 120000
index fc01ea3..0000000
--- a/tests/data_files/ecdsa_secp256r1.key
+++ /dev/null
@@ -1 +0,0 @@
-ec_256_prv.pem
\ No newline at end of file
diff --git a/tests/data_files/ecdsa_secp256r1.key b/tests/data_files/ecdsa_secp256r1.key
new file mode 100644
index 0000000..e42dd4a
--- /dev/null
+++ b/tests/data_files/ecdsa_secp256r1.key
@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIEnJqMGMS4hWOMQxzx3xyZQTFgm1gNT9Q6DKsX2y8T7uoAoGCCqGSM49
+AwEHoUQDQgAEd3Jlb4FLOZJ51eHxeB+sbwmaPFyhsONTUYNLCLZeC1clkM2vj3aT
+YbzzSs/BHl4HToQmvd4Evm5lOUVElhfeRQ==
+-----END EC PRIVATE KEY-----
diff --git a/tests/data_files/ecdsa_secp384r1.key b/tests/data_files/ecdsa_secp384r1.key
deleted file mode 120000
index ff72d53..0000000
--- a/tests/data_files/ecdsa_secp384r1.key
+++ /dev/null
@@ -1 +0,0 @@
-ec_384_prv.pem
\ No newline at end of file
diff --git a/tests/data_files/ecdsa_secp384r1.key b/tests/data_files/ecdsa_secp384r1.key
new file mode 100644
index 0000000..7890759
--- /dev/null
+++ b/tests/data_files/ecdsa_secp384r1.key
@@ -0,0 +1,6 @@
+-----BEGIN EC PRIVATE KEY-----
+MIGkAgEBBDA/XY2b4oC1aWzFzJ+Uz4r35rYd1lkrKrKzpMYHRQQX7DJ9zcrtfBAF
+PXGaBXTwp2qgBwYFK4EEACKhZANiAATZxmK1C6KcpHmQRQ4EOur08MabFWdtES9i
+KnHJMFmvmZaRxWgNK0TREVedsS9KQTou1cRfz7Z7W2PgC5Hr5Z0JprGsLAxCgqoS
+MX7VkU+Zm8SIuxMug0LMNvLKXjN5x0c=
+-----END EC PRIVATE KEY-----
diff --git a/tests/data_files/ecdsa_secp521r1.key b/tests/data_files/ecdsa_secp521r1.key
deleted file mode 120000
index b047f03..0000000
--- a/tests/data_files/ecdsa_secp521r1.key
+++ /dev/null
@@ -1 +0,0 @@
-ec_521_prv.pem
\ No newline at end of file
diff --git a/tests/data_files/ecdsa_secp521r1.key b/tests/data_files/ecdsa_secp521r1.key
new file mode 100644
index 0000000..144bb44
--- /dev/null
+++ b/tests/data_files/ecdsa_secp521r1.key
@@ -0,0 +1,7 @@
+-----BEGIN EC PRIVATE KEY-----
+MIHcAgEBBEIBsbatB7t55zINpZhg6ijgVShPYFjyed5mbgbUNdKve9oo2Z+ke33Q
+lj4WsAcweO6LijjZZqWC9G0Z/5XfOtloWq6gBwYFK4EEACOhgYkDgYYABAAd4ULV
+T2nrA47kt6+dPKB3Nv2c9xnrNU1ph57n88E2+w+/nwj4a+X6Eo7BoFHT5sZD6Fra
+j/rPNmPCYL0shEtvVgDO6OSKnmXQnK3YnyNd7gXzuKZGvnFfH2fVtDTg/yOh/Afv
+d0AZPkDu/287zf12WqkVUDNST+TyBfVETiksTC9qwQ==
+-----END EC PRIVATE KEY-----