diff --git a/lib/python/qmk/cli/generate/config_h.py b/lib/python/qmk/cli/generate/config_h.py
index 64d4db6ffe..828785ea48 100755
--- a/lib/python/qmk/cli/generate/config_h.py
+++ b/lib/python/qmk/cli/generate/config_h.py
@@ -15,7 +15,12 @@ from qmk.constants import GPL2_HEADER_C_LIKE, GENERATED_HEADER_C_LIKE
 
 
 def generate_define(define, value=None):
+    is_keymap = cli.args.filename
     value = f' {value}' if value is not None else ''
+    if is_keymap:
+        return f"""
+#undef {define}
+#define {define}{value}"""
     return f"""
 #ifndef {define}
 #    define {define}{value}
diff --git a/lib/python/qmk/cli/generate/rules_mk.py b/lib/python/qmk/cli/generate/rules_mk.py
index fc272da6c6..5291556109 100755
--- a/lib/python/qmk/cli/generate/rules_mk.py
+++ b/lib/python/qmk/cli/generate/rules_mk.py
@@ -14,6 +14,12 @@ from qmk.path import normpath, FileType
 from qmk.constants import GPL2_HEADER_SH_LIKE, GENERATED_HEADER_SH_LIKE
 
 
+def generate_rule(rules_key, rules_value):
+    is_keymap = cli.args.filename
+    rule_assignment_operator = '=' if is_keymap else '?='
+    return f'{rules_key} {rule_assignment_operator} {rules_value}'
+
+
 def process_mapping_rule(kb_info_json, rules_key, info_dict):
     """Return the rules.mk line(s) for a mapping rule.
     """
@@ -29,15 +35,15 @@ def process_mapping_rule(kb_info_json, rules_key, info_dict):
         return None
 
     if key_type in ['array', 'list']:
-        return f'{rules_key} ?= {" ".join(rules_value)}'
+        return generate_rule(rules_key, " ".join(rules_value))
     elif key_type == 'bool':
-        return f'{rules_key} ?= {"yes" if rules_value else "no"}'
+        return generate_rule(rules_key, "yes" if rules_value else "no")
     elif key_type == 'mapping':
-        return '\n'.join([f'{key} ?= {value}' for key, value in rules_value.items()])
+        return '\n'.join([generate_rule(key, value) for key, value in rules_value.items()])
     elif key_type == 'str':
-        return f'{rules_key} ?= "{rules_value}"'
+        return generate_rule(rules_key, f'"{rules_value}"')
 
-    return f'{rules_key} ?= {rules_value}'
+    return generate_rule(rules_key, rules_value)
 
 
 @cli.argument('filename', nargs='?', arg_only=True, type=FileType('r'), completer=FilesCompleter('.json'), help='A configurator export JSON to be compiled and flashed or a pre-compiled binary firmware file (bin/hex) to be flashed.')
@@ -77,21 +83,21 @@ def generate_rules_mk(cli):
         for feature, enabled in kb_info_json['features'].items():
             feature = feature.upper()
             enabled = 'yes' if enabled else 'no'
-            rules_mk_lines.append(f'{feature}_ENABLE ?= {enabled}')
+            rules_mk_lines.append(generate_rule(f'{feature}_ENABLE', enabled))
 
     # Set SPLIT_TRANSPORT, if needed
     if kb_info_json.get('split', {}).get('transport', {}).get('protocol') == 'custom':
-        rules_mk_lines.append('SPLIT_TRANSPORT ?= custom')
+        rules_mk_lines.append(generate_rule('SPLIT_TRANSPORT', 'custom'))
 
     # Set CUSTOM_MATRIX, if needed
     if kb_info_json.get('matrix_pins', {}).get('custom'):
         if kb_info_json.get('matrix_pins', {}).get('custom_lite'):
-            rules_mk_lines.append('CUSTOM_MATRIX ?= lite')
+            rules_mk_lines.append(generate_rule('CUSTOM_MATRIX', 'lite'))
         else:
-            rules_mk_lines.append('CUSTOM_MATRIX ?= yes')
+            rules_mk_lines.append(generate_rule('CUSTOM_MATRIX', 'yes'))
 
     if converter:
-        rules_mk_lines.append(f'CONVERT_TO ?= {converter}')
+        rules_mk_lines.append(generate_rule('CONVERT_TO', converter))
 
     # Show the results
     dump_lines(cli.args.output, rules_mk_lines)