diff --git a/src/main/python/keyboard_comm.py b/src/main/python/keyboard_comm.py
index 82772f1..1fd3160 100644
--- a/src/main/python/keyboard_comm.py
+++ b/src/main/python/keyboard_comm.py
@@ -28,6 +28,9 @@ CMD_VIAL_GET_ENCODER = 0x03
 CMD_VIAL_SET_ENCODER = 0x04
 CMD_VIAL_GET_KEYMAP_FAST = 0x05
 
+# how much of a macro we can read/write per packet
+MACRO_CHUNK = 28
+
 
 class Keyboard:
     """ Low-level communication with a vial-enabled keyboard """
@@ -177,10 +180,9 @@ class Keyboard:
         self.macro_memory = struct.unpack(">H", data[1:3])[0]
 
         self.macro = b""
-        # now retrieve the entire buffer, 28 bytes at a time, as that is what fits into a packet
-        chunk = 28
-        for x in range(0, self.macro_memory, chunk):
-            sz = min(chunk, self.macro_memory - x)
+        # now retrieve the entire buffer, MACRO_CHUNK bytes at a time, as that is what fits into a packet
+        for x in range(0, self.macro_memory, MACRO_CHUNK):
+            sz = min(MACRO_CHUNK, self.macro_memory - x)
             data = self.usb_send(self.dev, struct.pack(">BHB", CMD_VIA_MACRO_GET_BUFFER, x, sz))
             self.macro += data[4:4+sz]
 
@@ -202,6 +204,14 @@ class Keyboard:
             self.layout_options = options
             self.usb_send(self.dev, struct.pack(">BBI", CMD_VIA_SET_KEYBOARD_VALUE, VIA_LAYOUT_OPTIONS, options))
 
+    def set_macro(self, data):
+        if len(data) > self.macro_memory:
+            raise RuntimeError("the macro is too big: got {} max {}".format(len(data), self.macro_memory))
+
+        for x, chunk in enumerate(chunks(data, MACRO_CHUNK)):
+            off = x * MACRO_CHUNK
+            self.usb_send(self.dev, struct.pack(">BHB", CMD_VIA_MACRO_SET_BUFFER, off, len(chunk)) + chunk)
+
     def save_layout(self):
         """ Serializes current layout to a binary """
 
diff --git a/src/main/python/macro_recorder.py b/src/main/python/macro_recorder.py
index 07a206b..5e58bfc 100644
--- a/src/main/python/macro_recorder.py
+++ b/src/main/python/macro_recorder.py
@@ -198,10 +198,11 @@ class MacroRecorder(BasicEditor):
         buttons = QHBoxLayout()
         buttons.addWidget(self.lbl_memory)
         buttons.addStretch()
-        btn_save = QPushButton(tr("MacroRecorder", "Save"))
+        self.btn_save = QPushButton(tr("MacroRecorder", "Save"))
+        self.btn_save.clicked.connect(self.on_save)
         btn_revert = QPushButton(tr("MacroRecorder", "Revert"))
         btn_revert.clicked.connect(self.on_revert)
-        buttons.addWidget(btn_save)
+        buttons.addWidget(self.btn_save)
         buttons.addWidget(btn_revert)
 
         self.addWidget(self.tabs)
@@ -267,6 +268,8 @@ class MacroRecorder(BasicEditor):
     def on_change(self):
         memory = len(self.serialize())
         self.lbl_memory.setText("Memory used by macros: {}/{}".format(memory, self.keyboard.macro_memory))
+        self.btn_save.setEnabled(memory <= self.keyboard.macro_memory)
+        self.lbl_memory.setStyleSheet("QLabel { color: red; }" if memory > self.keyboard.macro_memory else "")
 
     def deserialize(self, data):
         macros = data.split(b"\x00")
@@ -285,3 +288,6 @@ class MacroRecorder(BasicEditor):
     def on_revert(self):
         self.keyboard.reload_macros()
         self.deserialize(self.keyboard.macro)
+
+    def on_save(self):
+        self.keyboard.set_macro(self.serialize())