diff --git a/src/libguac/client-handlers.c b/src/libguac/client-handlers.c
index 4f1e253f..7a69d72d 100644
--- a/src/libguac/client-handlers.c
+++ b/src/libguac/client-handlers.c
@@ -52,6 +52,7 @@ __guac_instruction_handler_mapping __guac_instruction_handler_map[] = {
    {"disconnect", __guac_handle_disconnect},
    {"size",       __guac_handle_size},
    {"file",       __guac_handle_file},
+   {"ack",        __guac_handle_ack},
    {"blob",       __guac_handle_blob},
    {"end",        __guac_handle_end},
    {NULL,         NULL}
@@ -166,6 +167,29 @@ int __guac_handle_file(guac_client* client, guac_instruction* instruction) {
     return 0;
 }
 
+int __guac_handle_ack(guac_client* client, guac_instruction* instruction) {
+
+    guac_stream* stream;
+
+    /* Validate stream index */
+    int stream_index = atoi(instruction->argv[0]);
+    if (stream_index < 0 || stream_index >= GUAC_CLIENT_MAX_STREAMS)
+        return 0;
+
+    stream = &(client->__streams[stream_index]);
+
+    /* Validate initialization of stream */
+    if (stream->index == GUAC_CLIENT_CLOSED_STREAM_INDEX)
+        return 0;
+
+    /* If handler defined, call it */
+    if (client->ack_handler)
+        return client->ack_handler(client, stream, instruction->argv[1],
+                atoi(instruction->argv[2]));
+
+    return 0;
+}
+
 int __guac_handle_blob(guac_client* client, guac_instruction* instruction) {
 
     guac_stream* stream;
diff --git a/src/libguac/client-handlers.h b/src/libguac/client-handlers.h
index 28ac7fa2..b09efaab 100644
--- a/src/libguac/client-handlers.h
+++ b/src/libguac/client-handlers.h
@@ -106,6 +106,13 @@ int __guac_handle_clipboard(guac_client* client, guac_instruction* instruction);
  */
 int __guac_handle_file(guac_client* client, guac_instruction* instruction);
 
+/**
+ * Internal initial handler for the ack instruction. When a ack instruction
+ * is received, this handler will be called. The client's ack handler will
+ * be invoked if defined.
+ */
+int __guac_handle_ack(guac_client* client, guac_instruction* instruction);
+
 /**
  * Internal initial handler for the blob instruction. When a blob instruction
  * is received, this handler will be called. The client's blob handler will
diff --git a/src/libguac/guacamole/client.h b/src/libguac/guacamole/client.h
index c738ee46..f1f79d4d 100644
--- a/src/libguac/guacamole/client.h
+++ b/src/libguac/guacamole/client.h
@@ -44,6 +44,7 @@
 #include "instruction.h"
 #include "layer.h"
 #include "pool.h"
+#include "protocol.h"
 #include "socket.h"
 #include "stream.h"
 #include "timestamp.h"
@@ -105,6 +106,12 @@ typedef int guac_client_file_handler(guac_client* client, guac_stream* stream,
 typedef int guac_client_blob_handler(guac_client* client, guac_stream* stream,
         void* data, int length);
 
+/**
+ * Handler for Guacamole stream ack events.
+ */
+typedef int guac_client_ack_handler(guac_client* client, guac_stream* stream,
+        char* error, guac_protocol_status status);
+
 /**
  * Handler for Guacamole stream end events.
  */
@@ -401,6 +408,25 @@ struct guac_client {
      */
     guac_client_file_handler* file_handler;
 
+    /**
+     * Handler for ack events sent by the Guacamole web-client.
+     *
+     * The handler takes a guac_stream which contains the stream index and
+     * will persist through the duration of the transfer, a string containing
+     * the error or status message, and a status code.
+     *
+     * Example:
+     * @code
+     *     int ack_handler(guac_client* client, guac_stream* stream,
+     *             char* error, guac_protocol_status status);
+     *
+     *     int guac_client_init(guac_client* client, int argc, char** argv) {
+     *         client->ack_handler = ack_handler;
+     *     }
+     * @endcode
+     */
+    guac_client_ack_handler* ack_handler;
+
     /**
      * Handler for blob events sent by the Guacamole web-client.
      *