diff --git a/libcaf_openssl/src/openssl/session.cpp b/libcaf_openssl/src/openssl/session.cpp
index a5512a5264..1a2a1622c2 100644
--- a/libcaf_openssl/src/openssl/session.cpp
+++ b/libcaf_openssl/src/openssl/session.cpp
@@ -5,7 +5,10 @@
 #include "caf/openssl/session.hpp"
 
 #include <optional>
+
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
 #include <openssl/decoder.h>
+#endif
 
 CAF_PUSH_WARNINGS
 #include <openssl/err.h>
@@ -79,6 +82,7 @@ std::optional<std::string> contents_from_indirect_envvar(const std::string& str)
 // If the input is a string like `env:SOME_VARIABLE` and the environment variable
 // `SOME_VARIABLE` exists, returns a string with the value of `SOME_VARIABLE`.
 std::optional<std::string> tmpfile_from_string(const std::string& content) {
+  std::cout << "content:\n" << content << std::endl;
   auto filename = std::string{"/tmp/caf-openssl.XXXXXX"};
   ::mkstemp(&filename[0]);
   std::ofstream ofs(filename);
@@ -262,9 +266,10 @@ SSL_CTX* session::create_ssl_context() {
     // memory and the implementation of `SSL_CTX_use_certificate_chain_file`
     // is huge, so we write into a temporary file.
     if (auto filename = pem_file_from_envvar(cfg.openssl_certificate)) {
+      std::cout << *filename << std::endl;
       if (SSL_CTX_use_certificate_chain_file(ctx, filename->c_str())
              != 1)
-        CAF_RAISE_ERROR("cannot load certificate from environt variable");
+        CAF_RAISE_ERROR("cannot load certificate from environment variable");
     } else if (!cfg.openssl_certificate.empty()
         && SSL_CTX_use_certificate_chain_file(ctx,
                                               cfg.openssl_certificate.c_str())
@@ -277,20 +282,20 @@ SSL_CTX* session::create_ssl_context() {
       SSL_CTX_set_default_passwd_cb_userdata(ctx, this);
     }
     if (auto var = pem_string_from_envvar(cfg.openssl_key)) {
-#if OPENSSL_VERSION_NUMBER < 0x10101000L
+#if OPENSSL_VERSION_NUMBER < 0x30000000L
       // BIO_new_mem_buf just creates a read-only view, so we don't need
       // to free it afterwards.
-      kbio = BIO_new_mem_buf(var->data(), -1);
+      auto* kbio = BIO_new_mem_buf(var->data(), -1);
       if (!kbio)
-        CAF_RAISE_ERROR("");
+        CAF_RAISE_ERROR("failed to construct OpenSSL BIO");
       // This function was deprecated in favor of the OSSL_DECODER API
       // introduced in OpenSSL 3.0, but that is not available on
       // Debian Bullseye.
-      rsa = PEM_read_bio_RSAPrivateKey(kbio, NULL, 0, NULL);
+      auto* rsa = PEM_read_bio_RSAPrivateKey(kbio, NULL, 0, NULL);
       if (rsa != NULL)
-        CAF_RAISE_CAF_RAISE_ERROR("invalid private key");
+        CAF_RAISE_ERROR("invalid private key");
       SSL_CTX_use_RSAPrivateKey(ctx, rsa);
-#else /* OPENSSL_VERSION_NUMBER < 0x10101000L */
+#else /* OPENSSL_VERSION_NUMBER < 0x30000000L */
       EVP_PKEY *pkey = nullptr;
       const char *format = "PEM";   // NULL for any format
       const char *structure = nullptr; // Any structure
@@ -311,7 +316,7 @@ SSL_CTX* session::create_ssl_context() {
       // Use the private key.
       SSL_CTX_use_PrivateKey(ctx, pkey);
       OSSL_DECODER_CTX_free(dctx);
-#endif /* OPENSSL_VERSION_NUMBER < 0x10101000L */
+#endif /* OPENSSL_VERSION_NUMBER < 0x30000000L */
     }
     else if (!cfg.openssl_key.empty()
         && SSL_CTX_use_PrivateKey_file(ctx, cfg.openssl_key.c_str(),