diff --git a/config/example-extras.cfg b/config/example-extras.cfg
index 8b1cad33..1e5776f9 100644
--- a/config/example-extras.cfg
+++ b/config/example-extras.cfg
@@ -976,6 +976,14 @@
 #   a macro MY_DELAY with gcode "G4 P{DELAY}" then the command
 #   "MY_DELAY DELAY=100" would evaluate to "G4 P100". This parameter
 #   must be provided.
+#default_parameter_<parameter>:
+#   One may define any number of options with a "default_parameter_"
+#   prefix. Use this to define default values for g-code parameters.
+#   For example, if one were to define the macro MY_DELAY with gcode
+#   "G4 P{DELAY}" along with "default_paramter_DELAY = 50" then the
+#   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.
 
 
 # Replicape support - see the generic-replicape.cfg file for further
diff --git a/klippy/extras/gcode_macro.py b/klippy/extras/gcode_macro.py
index 5e93e360..7fe4bfed 100644
--- a/klippy/extras/gcode_macro.py
+++ b/klippy/extras/gcode_macro.py
@@ -5,6 +5,8 @@
 # This file may be distributed under the terms of the GNU GPLv3 license.
 import logging
 
+DEFAULT_PREFIX = 'default_parameter_'
+
 class GCodeMacro:
     def __init__(self, config):
         self.alias = config.get_name().split()[1].upper()
@@ -17,14 +19,18 @@ class GCodeMacro:
         except self.gcode.error as e:
             raise config.error(str(e))
         self.in_script = False
+        self.kwparams = { o[len(DEFAULT_PREFIX):].upper(): config.get(o)
+                          for o in config.get_prefix_options(DEFAULT_PREFIX) }
     cmd_desc = "G-Code macro"
     def cmd(self, params):
         if self.in_script:
             raise self.gcode.error(
                 "Macro %s called recursively" % (self.alias,))
         script = ""
+        kwparams = dict(self.kwparams)
+        kwparams.update(params)
         try:
-            script = self.script.format(**params)
+            script = self.script.format(**kwparams)
         except Exception:
             msg = "Macro %s script formatting failed" % (self.alias,)
             logging.exception(msg)