diff --git a/config/example-extras.cfg b/config/example-extras.cfg
index b4ec6750..d3e1f1c7 100644
--- a/config/example-extras.cfg
+++ b/config/example-extras.cfg
@@ -1487,6 +1487,13 @@
 #   command "MY_DELAY" would evaluate to "G4 P50". The default is to
 #   require that all parameters used in the gcode script be present in
 #   the command invoking the macro.
+#variable_<name>:
+#   One may specify any number of options with a "variable_" prefix.
+#   The given variable name will then be available during macro
+#   expansion. For example, a config with "variable_my_name = zebra"
+#   might have a gcode config containing "M117 My name is {my_name}".
+#   Variables can be changed at run-time using the SET_GCODE_VARIABLE
+#   command.
 
 
 # Enable the "M118" and "RESPOND" extended commands.
diff --git a/docs/G-Codes.md b/docs/G-Codes.md
index 3c885677..966371e7 100644
--- a/docs/G-Codes.md
+++ b/docs/G-Codes.md
@@ -176,6 +176,14 @@ The following standard commands are supported:
 - `STATUS`: Report the Klipper host software status.
 - `HELP`: Report the list of available extended G-Code commands.
 
+## G-Code Macro Commands
+
+The following command is available when a "gcode_macro" config section
+is enabled:
+- `SET_GCODE_VARIABLE MACRO=<macro_name> VARIABLE=<name>
+  VALUE=<value>`: This command allows one to change the value of a
+  gcode_macro variable at run-time.
+
 ## Custom Pin Commands
 
 The following command is available when an "output_pin" config section
diff --git a/klippy/extras/gcode_macro.py b/klippy/extras/gcode_macro.py
index 57b2153d..a29e1248 100644
--- a/klippy/extras/gcode_macro.py
+++ b/klippy/extras/gcode_macro.py
@@ -77,17 +77,37 @@ def load_config(config):
 
 class GCodeMacro:
     def __init__(self, config):
-        self.alias = config.get_name().split()[1].upper()
+        name = config.get_name().split()[1]
+        self.alias = name.upper()
         printer = config.get_printer()
         config.get('gcode')
         gcode_macro = printer.try_load_module(config, 'gcode_macro')
         self.template = gcode_macro.load_template(config, 'gcode')
         self.gcode = printer.lookup_object('gcode')
         self.gcode.register_command(self.alias, self.cmd, desc=self.cmd_desc)
+        self.gcode.register_mux_command("SET_GCODE_VARIABLE", "MACRO",
+                                        name, self.cmd_SET_GCODE_VARIABLE,
+                                        desc=self.cmd_SET_GCODE_VARIABLE_help)
         self.in_script = False
         prefix = 'default_parameter_'
         self.kwparams = { o[len(prefix):].upper(): config.get(o)
                           for o in config.get_prefix_options(prefix) }
+        prefix = 'variable_'
+        self.variables = { o[len(prefix):]: config.get(o)
+                           for o in config.get_prefix_options(prefix) }
+    def get_status(self, eventtime):
+        return dict(self.variables)
+    cmd_SET_GCODE_VARIABLE_help = "Set the value of a G-Code macro variable"
+    def cmd_SET_GCODE_VARIABLE(self, params):
+        variable = self.gcode.get_str('VARIABLE', params)
+        value = self.gcode.get_str('VALUE', params)
+        if variable not in self.variables:
+            if variable in self.kwparams:
+                self.kwparams[variable] = value
+                return
+            raise self.gcode.error("Unknown gcode_macro variable '%s'" % (
+                variable,))
+        self.variables[variable] = value
     cmd_desc = "G-Code macro"
     def cmd(self, params):
         if self.in_script:
@@ -95,6 +115,7 @@ class GCodeMacro:
                 "Macro %s called recursively" % (self.alias,))
         kwparams = dict(self.kwparams)
         kwparams.update(params)
+        kwparams.update(self.variables)
         kwparams['printer'] = self.template.create_status_wrapper()
         kwparams['params'] = params
         self.in_script = True