diff --git a/src/libguac/client.c b/src/libguac/client.c
index 9738c0c2..cd4b5463 100644
--- a/src/libguac/client.c
+++ b/src/libguac/client.c
@@ -671,6 +671,36 @@ static void* __webp_support_callback(guac_user* user, void* data) {
 }
 #endif
 
+/**
+ * A callback function which is invoked by guac_client_owner_supports_msg()
+ * to determine if the owner of a client supports the "msg" instruction,
+ * returning zero if the user does not support the instruction or non-zero if
+ * the user supports it.
+ * 
+ * @param user
+ *     The guac_user that will be checked for "msg" instruction support.
+ * 
+ * @param data
+ *     Data provided to the callback. This value is never used within this
+ *     callback.
+ * 
+ * @return
+ *     A non-zero integer if the provided user who owns the connection supports
+ *     the "msg" instruction, or zero if the user does not. The integer is cast
+ *     as a void*.
+ */
+static void* guac_owner_supports_msg_callback(guac_user* user, void* data) {
+
+    return (void*) ((intptr_t) guac_user_supports_msg(user));
+
+}
+
+int guac_client_owner_supports_msg(guac_client* client) {
+
+    return (int) ((intptr_t) guac_client_for_owner(client, guac_owner_supports_msg_callback, NULL));
+
+}
+
 /**
  * A callback function which is invoked by guac_client_owner_supports_required()
  * to determine if the owner of a client supports the "required" instruction,
diff --git a/src/libguac/guacamole/client.h b/src/libguac/guacamole/client.h
index 4ffe5cf4..2067c5cd 100644
--- a/src/libguac/guacamole/client.h
+++ b/src/libguac/guacamole/client.h
@@ -708,6 +708,21 @@ void guac_client_stream_webp(guac_client* client, guac_socket* socket,
         guac_composite_mode mode, const guac_layer* layer, int x, int y,
         cairo_surface_t* surface, int quality, int lossless);
 
+/**
+ * Returns whether the owner of the given client supports the "msg"
+ * instruction, returning non-zero if the client owner does support the
+ * instruction, or zero if the owner does not.
+ * 
+ * @param client
+ *     The Guacamole client whose owner should be checked for supporting
+ *     the "msg" instruction.
+ * 
+ * @return 
+ *     Non-zero if the owner of the given client supports the "msg"
+ *     instruction, zero otherwise.
+ */
+int guac_client_owner_supports_msg(guac_client* client);
+
 /**
  * Returns whether the owner of the given client supports the "required"
  * instruction, returning non-zero if the client owner does support the
diff --git a/src/libguac/guacamole/protocol-constants.h b/src/libguac/guacamole/protocol-constants.h
index 13d7f680..a8fc9777 100644
--- a/src/libguac/guacamole/protocol-constants.h
+++ b/src/libguac/guacamole/protocol-constants.h
@@ -38,7 +38,7 @@
  * This version is passed by the __guac_protocol_send_args() function from the
  * server to the client during the client/server handshake.
  */
-#define GUACAMOLE_PROTOCOL_VERSION "VERSION_1_3_0"
+#define GUACAMOLE_PROTOCOL_VERSION "VERSION_1_5_0"
 
 /**
  * The maximum number of bytes that should be sent in any one blob instruction
diff --git a/src/libguac/guacamole/protocol-types.h b/src/libguac/guacamole/protocol-types.h
index 51652d2b..1cb1de25 100644
--- a/src/libguac/guacamole/protocol-types.h
+++ b/src/libguac/guacamole/protocol-types.h
@@ -306,7 +306,13 @@ typedef enum guac_protocol_version {
      * allowing connections in guacd to request information from the client and
      * await a response.
      */
-    GUAC_PROTOCOL_VERSION_1_3_0 = 0x010300
+    GUAC_PROTOCOL_VERSION_1_3_0 = 0x010300,
+
+    /**
+     * Protocol version 1.5.0, which supports the "msg" instruction, allowing
+     * messages to be sent to the client.
+     */
+    GUAC_PROTOCOL_VERSION_1_5_0 = 0x010500
 
 } guac_protocol_version;
 
diff --git a/src/libguac/guacamole/protocol.h b/src/libguac/guacamole/protocol.h
index 362351c5..73578ba7 100644
--- a/src/libguac/guacamole/protocol.h
+++ b/src/libguac/guacamole/protocol.h
@@ -171,6 +171,21 @@ int guac_protocol_send_log(guac_socket* socket, const char* format, ...);
 int vguac_protocol_send_log(guac_socket* socket, const char* format,
         va_list args);
 
+/**
+ * Sends the given string over the socket to be displayed on the client. Returns
+ * zero if the message was sent successfully or non-zero if an error occurs.
+ *
+ * @param socket
+ *     The guac_socket connection to send the message to.
+ *
+ * @param message
+ *     The message to send to the client.
+ *
+ * @return
+ *     Zero if the message is sent successfully; otherwise non-zero.
+ */
+int guac_protocol_send_msg(guac_socket* socket, const char* message);
+
 /**
  * Sends a mouse instruction over the given guac_socket connection.
  *
diff --git a/src/libguac/guacamole/user.h b/src/libguac/guacamole/user.h
index 963dbe68..8f6a2721 100644
--- a/src/libguac/guacamole/user.h
+++ b/src/libguac/guacamole/user.h
@@ -850,6 +850,17 @@ void guac_user_stream_webp(guac_user* user, guac_socket* socket,
         guac_composite_mode mode, const guac_layer* layer, int x, int y,
         cairo_surface_t* surface, int quality, int lossless);
 
+/**
+ * Returns whether the given user supports the "msg" instruction.
+ * 
+ * @param user
+ *     The Guacamole user to check for support of the "msg" instruction.
+ * 
+ * @return 
+ *     Non-zero if the user supports the "msg" instruction, otherwise zero.
+ */
+int guac_user_supports_msg(guac_user* user);
+
 /**
  * Returns whether the given user supports the "required" instruction.
  * 
diff --git a/src/libguac/protocol.c b/src/libguac/protocol.c
index 1c53c200..0745c415 100644
--- a/src/libguac/protocol.c
+++ b/src/libguac/protocol.c
@@ -65,6 +65,7 @@ guac_protocol_version_mapping guac_protocol_version_table[] = {
     { GUAC_PROTOCOL_VERSION_1_0_0,   "VERSION_1_0_0" },
     { GUAC_PROTOCOL_VERSION_1_1_0,   "VERSION_1_1_0" },
     { GUAC_PROTOCOL_VERSION_1_3_0,   "VERSION_1_3_0" },
+    { GUAC_PROTOCOL_VERSION_1_5_0,   "VERSION_1_5_0" },
     { GUAC_PROTOCOL_VERSION_UNKNOWN, NULL }
 };
 
@@ -658,6 +659,21 @@ int guac_protocol_send_log(guac_socket* socket, const char* format, ...) {
 
 }
 
+int guac_protocol_send_msg(guac_socket* socket, const char* message) {
+
+    int ret_val;
+
+    guac_socket_instruction_begin(socket);
+    ret_val =
+           guac_socket_write_string(socket, "3.msg,")
+        || __guac_socket_write_length_string(socket, message)
+        || guac_socket_write_string(socket, ";");
+
+    guac_socket_instruction_end(socket);
+    return ret_val;
+
+}
+
 int guac_protocol_send_file(guac_socket* socket, const guac_stream* stream,
         const char* mimetype, const char* name) {
 
diff --git a/src/libguac/tests/protocol/guac_protocol_version.c b/src/libguac/tests/protocol/guac_protocol_version.c
index 37f42e0f..f9b2fdf2 100644
--- a/src/libguac/tests/protocol/guac_protocol_version.c
+++ b/src/libguac/tests/protocol/guac_protocol_version.c
@@ -27,11 +27,11 @@
  */
 void test_guac_protocol__version_to_string() {
     
-    guac_protocol_version version_a = GUAC_PROTOCOL_VERSION_1_3_0;
+    guac_protocol_version version_a = GUAC_PROTOCOL_VERSION_1_5_0;
     guac_protocol_version version_b = GUAC_PROTOCOL_VERSION_1_0_0;
     guac_protocol_version version_c = GUAC_PROTOCOL_VERSION_UNKNOWN;
     
-    CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_a), "VERSION_1_3_0");
+    CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_a), "VERSION_1_5_0");
     CU_ASSERT_STRING_EQUAL(guac_protocol_version_to_string(version_b), "VERSION_1_0_0");
     CU_ASSERT_PTR_NULL(guac_protocol_version_to_string(version_c));
     
diff --git a/src/libguac/user.c b/src/libguac/user.c
index 4320ca77..d16f43b9 100644
--- a/src/libguac/user.c
+++ b/src/libguac/user.c
@@ -316,6 +316,15 @@ void guac_user_stream_webp(guac_user* user, guac_socket* socket,
 
 }
 
+int guac_user_supports_msg(guac_user* user) {
+
+    if (user == NULL)
+        return 0;
+
+    return (user->info.protocol_version >= GUAC_PROTOCOL_VERSION_1_5_0);
+
+}
+
 int guac_user_supports_required(guac_user* user) {
     
     if (user == NULL)