diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 66904fb..3838511 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -683,7 +683,7 @@
  *
  * The format is described in
  * https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format. */
-void SSL_CTX_set_keylog_bio(SSL_CTX *ctx, BIO *keylog_bio);
+OPENSSL_EXPORT void SSL_CTX_set_keylog_bio(SSL_CTX *ctx, BIO *keylog_bio);
 
 
 struct ssl_aead_ctx_st;