diff --git a/Makefile b/Makefile
index a6c3ee35b7a7..3c754c8fd34d 100644
--- a/Makefile
+++ b/Makefile
@@ -288,6 +288,13 @@ define PARSE_RULE
     endif
 endef
 
+# different from the common.mk version because this needs extra $ because
+# it's used in PARSE_KEYBOARD which is already really magic
+define USE_RULES
+    $$(if $$(filter $(1),$$(RULES_MK_LIST)),,$$(eval RULES_MK_LIST += $(1)))\
+    $$(eval include $(1))
+endef
+
 # $1 = Keyboard
 # Parses a rule in the format <keymap>:<target>
 # the keyboard is already known when entering this function
@@ -301,9 +308,9 @@ define PARSE_KEYBOARD
     DEFAULT_FOLDER := $$(CURRENT_KB)
 
     # We assume that every rules.mk will contain the full default value
-    $$(eval include $(ROOT_DIR)/keyboards/$$(CURRENT_KB)/rules.mk)
+    $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(CURRENT_KB)/rules.mk)
     ifneq ($$(DEFAULT_FOLDER),$$(CURRENT_KB))
-        $$(eval include $(ROOT_DIR)/keyboards/$$(DEFAULT_FOLDER)/rules.mk)
+        $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(DEFAULT_FOLDER)/rules.mk)
     endif
     CURRENT_KB := $$(DEFAULT_FOLDER)
 
@@ -328,27 +335,27 @@ define PARSE_KEYBOARD
     KEYBOARD_LAYOUTS :=
     ifneq ("$$(wildcard $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_5)/rules.mk)","")
       LAYOUTS :=
-      $$(eval include $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_5)/rules.mk)
+      $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_5)/rules.mk)
       KEYBOARD_LAYOUTS := $$(sort $$(LAYOUTS) $$(KEYBOARD_LAYOUTS))
     endif
     ifneq ("$$(wildcard $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_4)/rules.mk)","")
       LAYOUTS :=
-      $$(eval include $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_4)/rules.mk)
+      $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_4)/rules.mk)
       KEYBOARD_LAYOUTS := $$(sort $$(LAYOUTS) $$(KEYBOARD_LAYOUTS))
     endif
     ifneq ("$$(wildcard $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_3)/rules.mk)","")
       LAYOUTS :=
-      $$(eval include $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_3)/rules.mk)
+      $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_3)/rules.mk)
       KEYBOARD_LAYOUTS := $$(sort $$(LAYOUTS) $$(KEYBOARD_LAYOUTS))
     endif
     ifneq ("$$(wildcard $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_2)/rules.mk)","")
       LAYOUTS :=
-      $$(eval include $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_2)/rules.mk)
+      $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_2)/rules.mk)
       KEYBOARD_LAYOUTS := $$(sort $$(LAYOUTS) $$(KEYBOARD_LAYOUTS))
     endif
     ifneq ("$$(wildcard $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_1)/rules.mk)","")
       LAYOUTS :=
-      $$(eval include $(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_1)/rules.mk)
+      $(call USE_RULES,$(ROOT_DIR)/keyboards/$$(KEYBOARD_FOLDER_PATH_1)/rules.mk)
       KEYBOARD_LAYOUTS := $$(sort $$(LAYOUTS) $$(KEYBOARD_LAYOUTS))
     endif
 
@@ -357,6 +364,8 @@ define PARSE_KEYBOARD
 
     KEYMAPS := $$(sort $$(KEYMAPS) $$(LAYOUT_KEYMAPS))
 
+    $$(eval include $$(foreach RULES_MK,$$(RULES_MK_LIST),$$(wildcard $$(subst rules.mk,build.mk,$$(RULES_MK)))))
+
     # if the rule after removing the start of it is empty (we haven't specified a kemap or target)
     # compile all the keymaps
     ifeq ($$(RULE),)
diff --git a/build_keyboard.mk b/build_keyboard.mk
index b086420653f4..dcb41fa3fef7 100644
--- a/build_keyboard.mk
+++ b/build_keyboard.mk
@@ -76,19 +76,19 @@ endif
 
 # Pull in rules.mk files from all our subfolders
 ifneq ("$(wildcard $(KEYBOARD_PATH_5)/rules.mk)","")
-    include $(KEYBOARD_PATH_5)/rules.mk
+    $(call USE_RULES,$(KEYBOARD_PATH_5)/rules.mk)
 endif
 ifneq ("$(wildcard $(KEYBOARD_PATH_4)/rules.mk)","")
-    include $(KEYBOARD_PATH_4)/rules.mk
+    $(call USE_RULES,$(KEYBOARD_PATH_4)/rules.mk)
 endif
 ifneq ("$(wildcard $(KEYBOARD_PATH_3)/rules.mk)","")
-    include $(KEYBOARD_PATH_3)/rules.mk
+    $(call USE_RULES,$(KEYBOARD_PATH_3)/rules.mk)
 endif
 ifneq ("$(wildcard $(KEYBOARD_PATH_2)/rules.mk)","")
-    include $(KEYBOARD_PATH_2)/rules.mk
+    $(call USE_RULES,$(KEYBOARD_PATH_2)/rules.mk)
 endif
 ifneq ("$(wildcard $(KEYBOARD_PATH_1)/rules.mk)","")
-    include $(KEYBOARD_PATH_1)/rules.mk
+    $(call USE_RULES,$(KEYBOARD_PATH_1)/rules.mk)
 endif
 
 
@@ -315,7 +315,8 @@ ifeq ("$(USER_NAME)","")
 endif
 USER_PATH := users/$(USER_NAME)
 
--include $(USER_PATH)/rules.mk
+$(call USE_RULES,$(USER_PATH)/rules.mk,-)
+$(eval include $(foreach RULES_MK,$(RULES_MK_LIST),$(wildcard $(subst rules.mk,build.mk,$(RULES_MK)))))
 ifneq ("$(wildcard $(USER_PATH)/config.h)","")
     CONFIG_H += $(USER_PATH)/config.h
 endif
diff --git a/common.mk b/common.mk
index aea29a7a20e2..5bce3121a0d2 100644
--- a/common.mk
+++ b/common.mk
@@ -22,3 +22,8 @@ COMMON_VPATH += $(QUANTUM_PATH)/audio
 COMMON_VPATH += $(QUANTUM_PATH)/process_keycode
 COMMON_VPATH += $(QUANTUM_PATH)/api
 COMMON_VPATH += $(DRIVER_PATH)
+
+define USE_RULES
+    $(if $(filter $(1),$(RULES_MK_LIST)),,$(eval RULES_MK_LIST += $(1)))\
+    $(eval $(2)include $(1))
+endef
diff --git a/keyboards/ergodox_ez/build.mk b/keyboards/ergodox_ez/build.mk
new file mode 100644
index 000000000000..b40fe310f784
--- /dev/null
+++ b/keyboards/ergodox_ez/build.mk
@@ -0,0 +1,3 @@
+ifeq ($(strip $(RGB_MATRIX_ENABLE)), no)
+  SRC += i2c_master.c
+endif
diff --git a/keyboards/ergodox_ez/rules.mk b/keyboards/ergodox_ez/rules.mk
index 2882072a627d..2db6cdd30ca5 100644
--- a/keyboards/ergodox_ez/rules.mk
+++ b/keyboards/ergodox_ez/rules.mk
@@ -84,6 +84,7 @@ SLEEP_LED_ENABLE = no
 API_SYSEX_ENABLE = no
 RGBLIGHT_ENABLE = yes
 RGB_MATRIX_ENABLE = no # enable later
+
 DEBOUNCE_TYPE = eager_pr
 
 LAYOUTS = ergodox