diff --git a/apps/s_client.c b/apps/s_client.c
index 6a4b2daf2dc902f761cadceed95c0cecbd2cc25a..9efea79aaf58100e34b2247d78b4c57672d86cbb 100644
--- a/apps/s_client.c
+++ b/apps/s_client.c
@@ -227,7 +227,7 @@ static int c_brief=0;
 
 static unsigned char *generated_supp_data = NULL;
 
-static unsigned char *most_recent_supplemental_data = NULL;
+static const unsigned char *most_recent_supplemental_data = NULL;
 static size_t most_recent_supplemental_data_length = 0;
 
 static int server_provided_server_authz = 0;
diff --git a/apps/s_server.c b/apps/s_server.c
index 44acb1e79aee4c035de3051e5c2ef48f0ea990bb..35f30e4d23e6893b993b526c0a60d4ac84762b7d 100644
--- a/apps/s_server.c
+++ b/apps/s_server.c
@@ -231,7 +231,7 @@ static const unsigned char auth_ext_data[]={TLSEXT_AUTHZDATAFORMAT_dtcp};
 
 static unsigned char *generated_supp_data = NULL;
 
-static unsigned char *most_recent_supplemental_data = NULL;
+static const unsigned char *most_recent_supplemental_data = NULL;
 static size_t most_recent_supplemental_data_length = 0;
 
 static int client_provided_server_authz = 0;