diff --git a/openpgpsdk/src/openpgpsdk/openssl_crypto.c b/openpgpsdk/src/openpgpsdk/openssl_crypto.c
index d1573437d..086dad77a 100644
--- a/openpgpsdk/src/openpgpsdk/openssl_crypto.c
+++ b/openpgpsdk/src/openpgpsdk/openssl_crypto.c
@@ -22,6 +22,7 @@
 /** \file
  */
 
+#include <openssl/bio.h>
 #include <openssl/md5.h>
 #include <openssl/sha.h>
 #include <openssl/dsa.h>