diff --git a/programs/pkey/dh_server.c b/programs/pkey/dh_server.c
index 6ce1da2..53a299a 100644
--- a/programs/pkey/dh_server.c
+++ b/programs/pkey/dh_server.c
@@ -74,7 +74,7 @@
     mbedtls_net_context listen_fd, client_fd;
 
     unsigned char buf[2048];
-    unsigned char hash[20];
+    unsigned char hash[32];
     unsigned char buf2[2];
     const char *pers = "dh_server";