diff --git a/libguac/include/protocol.h b/libguac/include/protocol.h
index aeb4b109..e73db9a1 100644
--- a/libguac/include/protocol.h
+++ b/libguac/include/protocol.h
@@ -392,10 +392,13 @@ int guac_protocol_send_sync(guac_socket* socket, guac_timestamp timestamp);
  * @param radius The radius of the circle containing the arc.
  * @param startAngle The starting angle, in radians.
  * @param endAngle The ending angle, in radians.
+ * @param negative Zero if the arc should be drawn in order of increasing
+ *                 angle, non-zero otherwise.
  * @return Zero on success, non-zero on error.
  */
 int guac_protocol_send_arc(guac_socket* socket, const guac_layer* layer,
-        int x, int y, int radius, double startAngle, double endAngle);
+        int x, int y, int radius, double startAngle, double endAngle,
+        int negative);
 
 /**
  * Sends a cfill instruction over the given guac_socket connection.
diff --git a/libguac/src/protocol.c b/libguac/src/protocol.c
index 6ec0d069..4b7bcbd9 100644
--- a/libguac/src/protocol.c
+++ b/libguac/src/protocol.c
@@ -484,7 +484,8 @@ int guac_protocol_send_args(guac_socket* socket, const char** args) {
 
 
 int guac_protocol_send_arc(guac_socket* socket, const guac_layer* layer,
-        int x, int y, int radius, double startAngle, double endAngle) {
+        int x, int y, int radius, double startAngle, double endAngle,
+        int negative) {
 
     return
            guac_socket_write_string(socket, "3.arc,")
@@ -499,6 +500,8 @@ int guac_protocol_send_arc(guac_socket* socket, const guac_layer* layer,
         || __guac_socket_write_length_double(socket, startAngle)
         || guac_socket_write_string(socket, ",")
         || __guac_socket_write_length_double(socket, endAngle)
+        || guac_socket_write_string(socket, ",")
+        || guac_socket_write_string(socket, negative ? "1" : "0")
         || guac_socket_write_string(socket, ";");
 
 }