diff --git a/src/protocols/vnc/vnc.c b/src/protocols/vnc/vnc.c
index d13826d1..54e88dca 100644
--- a/src/protocols/vnc/vnc.c
+++ b/src/protocols/vnc/vnc.c
@@ -47,6 +47,7 @@
 #include <guacamole/socket.h>
 #include <guacamole/timestamp.h>
 #include <rfb/rfbclient.h>
+#include <rfb/rfbconfig.h>
 #include <rfb/rfbproto.h>
 
 #include <stdlib.h>
@@ -55,6 +56,7 @@
 
 char* GUAC_VNC_CLIENT_KEY = "GUAC_VNC";
 
+#if LIBVNCSERVER_VERSION_MAJOR >=0 && LIBVNCSERVER_VERSION_MINOR >= 9 && LIBVNCSERVER_VERSION_PATCHLEVEL >= 11
 /**
  * A callback function that is called by the VNC library prior to writing
  * data to a TLS-encrypted socket.  This returns the rfbBool FALSE value
@@ -110,6 +112,7 @@ static rfbBool guac_vnc_unlock_write_to_tls(rfbClient* rfb_client) {
     }
     return TRUE;
 }
+#endif
 
 rfbClient* guac_vnc_get_client(guac_client* client) {
 
@@ -124,9 +127,11 @@ rfbClient* guac_vnc_get_client(guac_client* client) {
     rfb_client->GotFrameBufferUpdate = guac_vnc_update;
     rfb_client->GotCopyRect = guac_vnc_copyrect;
 
+#if LIBVNCSERVER_VERSION_MAJOR >=0 && LIBVNCSERVER_VERSION_MINOR >= 9 && LIBVNCSERVER_VERSION_PATCHLEVEL >= 11
     /* TLS Locking and Unlocking */
     rfb_client->LockWriteToTLS = guac_vnc_lock_write_to_tls;
     rfb_client->UnlockWriteToTLS = guac_vnc_unlock_write_to_tls;
+#endif
 
     /* Do not handle clipboard and local cursor if read-only */
     if (vnc_settings->read_only == 0) {
@@ -242,8 +247,10 @@ void* guac_vnc_client_thread(void* data) {
     rfbClientLog = guac_vnc_client_log_info;
     rfbClientErr = guac_vnc_client_log_error;
 
+#if LIBVNCSERVER_VERSION_MAJOR >=0 && LIBVNCSERVER_VERSION_MINOR >= 9 && LIBVNCSERVER_VERSION_PATCHLEVEL >= 11
     /* Initialize the write lock */
     pthread_mutex_init(&(vnc_client->tls_lock), NULL);
+#endif
 
     /* Attempt connection */
     rfbClient* rfb_client = guac_vnc_get_client(client);
diff --git a/src/protocols/vnc/vnc.h b/src/protocols/vnc/vnc.h
index 31e78461..de9b3239 100644
--- a/src/protocols/vnc/vnc.h
+++ b/src/protocols/vnc/vnc.h
@@ -32,6 +32,7 @@
 #include <guacamole/client.h>
 #include <guacamole/layer.h>
 #include <rfb/rfbclient.h>
+#include <rfb/rfbconfig.h>
 
 #ifdef ENABLE_PULSE
 #include "pulse/pulse.h"
@@ -55,10 +56,12 @@ typedef struct guac_vnc_client {
      */
     pthread_t client_thread;
 
+#if LIBVNCSERVER_VERSION_MAJOR >=0 && LIBVNCSERVER_VERSION_MINOR >= 9 && LIBVNCSERVER_VERSION_PATCHLEVEL >= 11
     /**
      * The TLS mutex lock for the client.
      */
     pthread_mutex_t tls_lock;
+#endif
 
     /**
      * The underlying VNC client.