diff --git a/CMakeLists.txt b/CMakeLists.txt
index 10b5d6e..5dcd179 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,7 @@ project(olm VERSION 3.2.8 LANGUAGES CXX C)
 
 option(OLM_TESTS "Build tests" ON)
 option(BUILD_SHARED_LIBS "Build as a shared library" ON)
-option(OLM_USE_OPENSSL "Use OpenSSL instead of bundled crypto-algorithms" OFF)
+option(OLM_USE_OPENSSL "Use OpenSSL instead of bundled crypto-algorithms and curve25519-donna" OFF)
 option(OLM_USE_LIBRESSL "Use LibreSSL instead of bundled crypto-algorithms" OFF)
 
 add_definitions(-DOLMLIB_VERSION_MAJOR=${PROJECT_VERSION_MAJOR})
@@ -47,9 +47,7 @@ add_library(olm
     src/megolm.c
     src/olm.cpp
     src/outbound_group_session.c
-    src/pickle_encoding.c
-
-    lib/curve25519-donna/curve25519-donna.c)
+    src/pickle_encoding.c)
 add_library(Olm::Olm ALIAS olm)
 
 if(OLM_USE_OPENSSL)
@@ -60,8 +58,11 @@ elseif(OLM_USE_LIBRESSL)
     find_package(LibreSSL REQUIRED)
     target_link_libraries(olm LibreSSL::Crypto)
     target_compile_definitions(olm PRIVATE OLM_USE_LIBRESSL)
+    target_sources(olm PRIVATE
+        lib/curve25519-donna/curve25519-donna.c)
 else()
     target_sources(olm PRIVATE
+        lib/curve25519-donna/curve25519-donna.c
         lib/crypto-algorithms/aes.c
         lib/crypto-algorithms/sha256.c)
 endif()
diff --git a/src/crypto.cpp b/src/crypto.cpp
index 5e543c7..74a59ed 100644
--- a/src/crypto.cpp
+++ b/src/crypto.cpp
@@ -131,6 +131,15 @@ void _olm_crypto_curve25519_generate_key(
     uint8_t const * random_32_bytes,
     struct _olm_curve25519_key_pair *key_pair
 ) {
+#ifdef OLM_USE_OPENSSL
+    EVP_PKEY *pkey = checked(EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, nullptr,
+                             random_32_bytes, 32));
+    size_t priv_len = CURVE25519_KEY_LENGTH;
+    size_t pub_len = CURVE25519_KEY_LENGTH;
+    checked(EVP_PKEY_get_raw_private_key(pkey, key_pair->private_key.private_key, &priv_len));
+    checked(EVP_PKEY_get_raw_public_key(pkey, key_pair->public_key.public_key, &pub_len));
+    EVP_PKEY_free(pkey);
+#else
     std::memcpy(
         key_pair->private_key.private_key, random_32_bytes,
         CURVE25519_KEY_LENGTH
@@ -140,6 +149,7 @@ void _olm_crypto_curve25519_generate_key(
         key_pair->private_key.private_key,
         CURVE25519_BASEPOINT
     );
+#endif
 }
 
 
@@ -148,7 +158,22 @@ void _olm_crypto_curve25519_shared_secret(
     const struct _olm_curve25519_public_key * their_key,
     std::uint8_t * output
 ) {
+#ifdef OLM_USE_OPENSSL
+    EVP_PKEY *pkey = checked(EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, nullptr,
+                             our_key->private_key.private_key, CURVE25519_KEY_LENGTH));
+    EVP_PKEY *peer = checked(EVP_PKEY_new_raw_public_key(EVP_PKEY_X25519, nullptr,
+                             their_key->public_key, CURVE25519_KEY_LENGTH));
+    EVP_PKEY_CTX *ctx = checked(EVP_PKEY_CTX_new(pkey, nullptr));
+    checked(EVP_PKEY_derive_init(ctx));
+    checked(EVP_PKEY_derive_set_peer(ctx, peer));
+    size_t shared_secret_length = CURVE25519_SHARED_SECRET_LENGTH;
+    checked(EVP_PKEY_derive(ctx, output, &shared_secret_length));
+    EVP_PKEY_CTX_free(ctx);
+    EVP_PKEY_free(peer);
+    EVP_PKEY_free(pkey);
+#else
     ::curve25519_donna(output, our_key->private_key.private_key, their_key->public_key);
+#endif
 }