diff --git a/include/openssl/bio.h b/include/openssl/bio.h
index 75afada..2168812 100644
--- a/include/openssl/bio.h
+++ b/include/openssl/bio.h
@@ -61,6 +61,7 @@
 
 #include <stdio.h>  /* For FILE */
 
+#include <openssl/buffer.h>
 #include <openssl/err.h> /* for ERR_print_errors_fp */
 #include <openssl/ex_data.h>
 #include <openssl/stack.h>