diff --git a/builddefs/build_full_test.mk b/builddefs/build_full_test.mk
index 964ba773d48..85ee0898ec2 100644
--- a/builddefs/build_full_test.mk
+++ b/builddefs/build_full_test.mk
@@ -17,7 +17,6 @@ $(TEST)_INC := \
 	tests/test_common/common_config.h
 
 $(TEST)_SRC := \
-	$(TMK_COMMON_SRC) \
 	$(QUANTUM_SRC) \
 	$(SRC) \
 	$(QUANTUM_PATH)/keymap_introspection.c \
@@ -31,7 +30,7 @@ $(TEST)_SRC := \
 	tests/test_common/test_logger.cpp \
 	$(patsubst $(ROOTDIR)/%,%,$(wildcard $(TEST_PATH)/*.cpp))
 
-$(TEST)_DEFS := $(TMK_COMMON_DEFS) $(OPT_DEFS) "-DKEYMAP_C=\"keymap.c\""
+$(TEST)_DEFS := $(OPT_DEFS) "-DKEYMAP_C=\"keymap.c\""
 
 $(TEST)_CONFIG := $(TEST_PATH)/config.h
 
diff --git a/builddefs/build_keyboard.mk b/builddefs/build_keyboard.mk
index 72c990abbba..e93ab97cc13 100644
--- a/builddefs/build_keyboard.mk
+++ b/builddefs/build_keyboard.mk
@@ -431,9 +431,6 @@ include $(PLATFORM_PATH)/common.mk
 
 SRC += $(patsubst %.c,%.clib,$(LIB_SRC))
 SRC += $(patsubst %.c,%.clib,$(QUANTUM_LIB_SRC))
-SRC += $(TMK_COMMON_SRC)
-OPT_DEFS += $(TMK_COMMON_DEFS)
-EXTRALDFLAGS += $(TMK_COMMON_LDFLAGS)
 
 -include $(PLATFORM_PATH)/$(PLATFORM_KEY)/bootloader.mk
 include $(PLATFORM_PATH)/$(PLATFORM_KEY)/platform.mk
diff --git a/keyboards/capsunlocked/cu75/keymaps/default/rules.mk b/keyboards/capsunlocked/cu75/keymaps/default/rules.mk
index bbd4c8c9fdc..aefb10a8b11 100644
--- a/keyboards/capsunlocked/cu75/keymaps/default/rules.mk
+++ b/keyboards/capsunlocked/cu75/keymaps/default/rules.mk
@@ -12,29 +12,3 @@ SLEEP_LED_ENABLE = yes
 
 ISSI_ENABLE = yes               # If the I2C pullup resistors aren't install this must be disabled
 WATCHDOG_ENABLE = no           # Resets keyboard if matrix_scan isn't run every 250ms
-
-
-ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
-endif
-
-ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
-endif
-
-
-# # Set the LFK78 hardware version. This is defined in rules.mk, but can be overidden here if desired
-# #
-# # RevB - first public release, uses atmega32u4, has audio, ISSI matrix split between RGB and backlight
-# # RevC/D - at90usb1286, no audio, ISSI device 0 is backlight, 4 is RGB
-# #
-# # Set to B, C or D
-# LFK_REV = D
-
-# ifeq ($(LFK_REV), B)
-# 	MCU = atmega32u4
-# else
-# 	MCU = at90usb1286
-# endif
-# OPT_DEFS += -DLFK_REV_$(LFK_REV)
-# OPT_DEFS += -DUSB_PRODUCT=\"LFK_Rev$(LFK_REV)\"
diff --git a/keyboards/capsunlocked/cu75/keymaps/iso/rules.mk b/keyboards/capsunlocked/cu75/keymaps/iso/rules.mk
index be27fed69c1..26239f265ee 100644
--- a/keyboards/capsunlocked/cu75/keymaps/iso/rules.mk
+++ b/keyboards/capsunlocked/cu75/keymaps/iso/rules.mk
@@ -12,29 +12,3 @@ SLEEP_LED_ENABLE = yes
 
 ISSI_ENABLE = no               # If the I2C pullup resistors aren't install this must be disabled
 WATCHDOG_ENABLE = yes           # Resets keyboard if matrix_scan isn't run every 250ms
-
-
-ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
-endif
-
-ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
-endif
-
-
-# # Set the LFK78 hardware version. This is defined in rules.mk, but can be overidden here if desired
-# #
-# # RevB - first public release, uses atmega32u4, has audio, ISSI matrix split between RGB and backlight
-# # RevC/D - at90usb1286, no audio, ISSI device 0 is backlight, 4 is RGB
-# #
-# # Set to B, C or D
-# LFK_REV = D
-
-# ifeq ($(LFK_REV), B)
-# 	MCU = atmega32u4
-# else
-# 	MCU = at90usb1286
-# endif
-# OPT_DEFS += -DLFK_REV_$(LFK_REV)
-# OPT_DEFS += -DUSB_PRODUCT=\"LFK_Rev$(LFK_REV)\"
diff --git a/keyboards/capsunlocked/cu75/post_rules.mk b/keyboards/capsunlocked/cu75/post_rules.mk
new file mode 100644
index 00000000000..a5d97466643
--- /dev/null
+++ b/keyboards/capsunlocked/cu75/post_rules.mk
@@ -0,0 +1,23 @@
+ifeq ($(strip $(ISSI_ENABLE)), yes)
+    OPT_DEFS += -DISSI_ENABLE
+endif
+
+ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
+    OPT_DEFS += -DWATCHDOG_ENABLE
+endif
+
+# # Set the LFK78 hardware version. This is defined in rules.mk, but can be overidden here if desired
+# #
+# # RevB - first public release, uses atmega32u4, has audio, ISSI matrix split between RGB and backlight
+# # RevC/D - at90usb1286, no audio, ISSI device 0 is backlight, 4 is RGB
+# #
+# # Set to B, C or D
+# LFK_REV = D
+
+# ifeq ($(LFK_REV), B)
+# 	MCU = atmega32u4
+# else
+# 	MCU = at90usb1286
+# endif
+# OPT_DEFS += -DLFK_REV_$(LFK_REV)
+# OPT_DEFS += -DUSB_PRODUCT=\"LFK_Rev$(LFK_REV)\"
diff --git a/keyboards/lfkeyboards/lfk78/post_rules.mk b/keyboards/lfkeyboards/lfk78/post_rules.mk
index 03f975b9df2..817a085f5e2 100644
--- a/keyboards/lfkeyboards/lfk78/post_rules.mk
+++ b/keyboards/lfkeyboards/lfk78/post_rules.mk
@@ -2,13 +2,13 @@
 SRC += TWIlib.c issi.c lighting.c
 
 ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
+    OPT_DEFS += -DISSI_ENABLE
 endif
 
 ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
+    OPT_DEFS += -DWATCHDOG_ENABLE
 endif
 
 ifeq ($(strip $(CAPSLOCK_LED)), yes)
-    TMK_COMMON_DEFS += -DCAPSLOCK_LED
+    OPT_DEFS += -DCAPSLOCK_LED
 endif
diff --git a/keyboards/lfkeyboards/lfkpad/post_rules.mk b/keyboards/lfkeyboards/lfkpad/post_rules.mk
index ad997587b2d..044d9754f15 100644
--- a/keyboards/lfkeyboards/lfkpad/post_rules.mk
+++ b/keyboards/lfkeyboards/lfkpad/post_rules.mk
@@ -1,7 +1,7 @@
 ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
+    OPT_DEFS += -DISSI_ENABLE
 endif
 
 ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
+    OPT_DEFS += -DWATCHDOG_ENABLE
 endif
diff --git a/keyboards/lfkeyboards/mini1800/reva/post_rules.mk b/keyboards/lfkeyboards/mini1800/reva/post_rules.mk
index ad997587b2d..044d9754f15 100644
--- a/keyboards/lfkeyboards/mini1800/reva/post_rules.mk
+++ b/keyboards/lfkeyboards/mini1800/reva/post_rules.mk
@@ -1,7 +1,7 @@
 ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
+    OPT_DEFS += -DISSI_ENABLE
 endif
 
 ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
+    OPT_DEFS += -DWATCHDOG_ENABLE
 endif
diff --git a/keyboards/lfkeyboards/mini1800/revc/post_rules.mk b/keyboards/lfkeyboards/mini1800/revc/post_rules.mk
index ad997587b2d..044d9754f15 100644
--- a/keyboards/lfkeyboards/mini1800/revc/post_rules.mk
+++ b/keyboards/lfkeyboards/mini1800/revc/post_rules.mk
@@ -1,7 +1,7 @@
 ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
+    OPT_DEFS += -DISSI_ENABLE
 endif
 
 ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
+    OPT_DEFS += -DWATCHDOG_ENABLE
 endif
diff --git a/keyboards/lfkeyboards/smk65/keymaps/default/rules.mk b/keyboards/lfkeyboards/smk65/keymaps/default/rules.mk
index 0cc9a7b76ba..1f0147bd38f 100644
--- a/keyboards/lfkeyboards/smk65/keymaps/default/rules.mk
+++ b/keyboards/lfkeyboards/smk65/keymaps/default/rules.mk
@@ -6,12 +6,3 @@ RGBLIGHT_ENABLE = no           # Enable keyboard RGB underglow
 
 ISSI_ENABLE = no               # If the I2C pullup resistors aren't install this must be disabled
 WATCHDOG_ENABLE = no           # Resets keyboard if matrix_scan isn't run every 250ms
-
-
-ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
-endif
-
-ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
-endif
diff --git a/keyboards/lfkeyboards/smk65/keymaps/iso/rules.mk b/keyboards/lfkeyboards/smk65/keymaps/iso/rules.mk
index 0cc9a7b76ba..1f0147bd38f 100644
--- a/keyboards/lfkeyboards/smk65/keymaps/iso/rules.mk
+++ b/keyboards/lfkeyboards/smk65/keymaps/iso/rules.mk
@@ -6,12 +6,3 @@ RGBLIGHT_ENABLE = no           # Enable keyboard RGB underglow
 
 ISSI_ENABLE = no               # If the I2C pullup resistors aren't install this must be disabled
 WATCHDOG_ENABLE = no           # Resets keyboard if matrix_scan isn't run every 250ms
-
-
-ifeq ($(strip $(ISSI_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DISSI_ENABLE
-endif
-
-ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
-endif
diff --git a/keyboards/lfkeyboards/smk65/post_rules.mk b/keyboards/lfkeyboards/smk65/post_rules.mk
new file mode 100644
index 00000000000..044d9754f15
--- /dev/null
+++ b/keyboards/lfkeyboards/smk65/post_rules.mk
@@ -0,0 +1,7 @@
+ifeq ($(strip $(ISSI_ENABLE)), yes)
+    OPT_DEFS += -DISSI_ENABLE
+endif
+
+ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
+    OPT_DEFS += -DWATCHDOG_ENABLE
+endif
diff --git a/keyboards/woodkeys/meira/post_rules.mk b/keyboards/woodkeys/meira/post_rules.mk
new file mode 100644
index 00000000000..5d85581c6ee
--- /dev/null
+++ b/keyboards/woodkeys/meira/post_rules.mk
@@ -0,0 +1,9 @@
+SRC += matrix.c TWIlib.c issi.c lighting.c
+
+#ifeq ($(strip $(ISSI_ENABLE)), yes)
+#    OPT_DEFS += -DISSI_ENABLE
+#endif
+
+#ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
+#    OPT_DEFS += -DWATCHDOG_ENABLE
+#endif
diff --git a/keyboards/woodkeys/meira/rules.mk b/keyboards/woodkeys/meira/rules.mk
index 20802b31790..63586244c0e 100644
--- a/keyboards/woodkeys/meira/rules.mk
+++ b/keyboards/woodkeys/meira/rules.mk
@@ -14,13 +14,4 @@ AUDIO_ENABLE = no           # Audio output
 
 CUSTOM_MATRIX = yes
 
-#ifeq ($(strip $(ISSI_ENABLE)), yes)
-#    TMK_COMMON_DEFS += -DISSI_ENABLE
-#endif
-
-#ifeq ($(strip $(WATCHDOG_ENABLE)), yes)
-#    TMK_COMMON_DEFS += -DWATCHDOG_ENABLE
-#endif
-SRC += matrix.c TWIlib.c issi.c lighting.c
-
 DEFAULT_FOLDER = woodkeys/meira/promicro
diff --git a/platforms/avr/printf.mk b/platforms/avr/printf.mk
index 060ad88c57c..c6490169d83 100644
--- a/platforms/avr/printf.mk
+++ b/platforms/avr/printf.mk
@@ -1,2 +1,2 @@
-TMK_COMMON_SRC += $(PLATFORM_COMMON_DIR)/xprintf.S
-TMK_COMMON_SRC += $(PLATFORM_COMMON_DIR)/printf.c
+SRC += $(PLATFORM_COMMON_DIR)/xprintf.S
+SRC += $(PLATFORM_COMMON_DIR)/printf.c
diff --git a/platforms/common.mk b/platforms/common.mk
index da0697e3b09..bbbe71ea126 100644
--- a/platforms/common.mk
+++ b/platforms/common.mk
@@ -1,6 +1,6 @@
 PLATFORM_COMMON_DIR = $(PLATFORM_PATH)/$(PLATFORM_KEY)
 
-TMK_COMMON_SRC +=	\
+SRC +=	\
 	$(PLATFORM_PATH)/suspend.c \
 	$(PLATFORM_PATH)/synchronization_util.c \
 	$(PLATFORM_PATH)/timer.c \
diff --git a/tmk_core/protocol.mk b/tmk_core/protocol.mk
index 2ae7aa9abea..d159dacc55b 100644
--- a/tmk_core/protocol.mk
+++ b/tmk_core/protocol.mk
@@ -1,4 +1,4 @@
-TMK_COMMON_SRC +=	\
+SRC +=	\
 	$(PROTOCOL_DIR)/host.c \
 	$(PROTOCOL_DIR)/report.c \
 	$(PROTOCOL_DIR)/usb_device_state.c \
@@ -7,7 +7,7 @@ TMK_COMMON_SRC +=	\
 SHARED_EP_ENABLE = no
 MOUSE_SHARED_EP ?= yes
 ifeq ($(strip $(KEYBOARD_SHARED_EP)), yes)
-    TMK_COMMON_DEFS += -DKEYBOARD_SHARED_EP
+    OPT_DEFS += -DKEYBOARD_SHARED_EP
     SHARED_EP_ENABLE = yes
     # With the current usb_descriptor.c code,
     # you can't share kbd without sharing mouse;
@@ -18,31 +18,31 @@ endif
 ifeq ($(strip $(MOUSE_ENABLE)), yes)
     OPT_DEFS += -DMOUSE_ENABLE
     ifeq ($(strip $(MOUSE_SHARED_EP)), yes)
-        TMK_COMMON_DEFS += -DMOUSE_SHARED_EP
+        OPT_DEFS += -DMOUSE_SHARED_EP
         SHARED_EP_ENABLE = yes
     endif
 endif
 
 ifeq ($(strip $(EXTRAKEY_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DEXTRAKEY_ENABLE
+    OPT_DEFS += -DEXTRAKEY_ENABLE
     SHARED_EP_ENABLE = yes
 endif
 
 ifeq ($(strip $(PROGRAMMABLE_BUTTON_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DPROGRAMMABLE_BUTTON_ENABLE
+    OPT_DEFS += -DPROGRAMMABLE_BUTTON_ENABLE
     SHARED_EP_ENABLE = yes
 endif
 
 ifeq ($(strip $(RAW_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DRAW_ENABLE
+    OPT_DEFS += -DRAW_ENABLE
 endif
 
 ifeq ($(strip $(CONSOLE_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DCONSOLE_ENABLE
+    OPT_DEFS += -DCONSOLE_ENABLE
 else
     # TODO: decouple this so other print backends can exist
-    TMK_COMMON_DEFS += -DNO_PRINT
-    TMK_COMMON_DEFS += -DNO_DEBUG
+    OPT_DEFS += -DNO_PRINT
+    OPT_DEFS += -DNO_DEBUG
 endif
 
 ifeq ($(strip $(NKRO_ENABLE)), yes)
@@ -51,51 +51,51 @@ ifeq ($(strip $(NKRO_ENABLE)), yes)
     else ifeq ($(strip $(BLUETOOTH_ENABLE)), yes)
         $(info NKRO is not currently supported with Bluetooth, and has been disabled.)
     else
-        TMK_COMMON_DEFS += -DNKRO_ENABLE
+        OPT_DEFS += -DNKRO_ENABLE
         SHARED_EP_ENABLE = yes
     endif
 endif
 
 ifeq ($(strip $(RING_BUFFERED_6KRO_REPORT_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DRING_BUFFERED_6KRO_REPORT_ENABLE
+    OPT_DEFS += -DRING_BUFFERED_6KRO_REPORT_ENABLE
 endif
 
 ifeq ($(strip $(NO_SUSPEND_POWER_DOWN)), yes)
-    TMK_COMMON_DEFS += -DNO_SUSPEND_POWER_DOWN
+    OPT_DEFS += -DNO_SUSPEND_POWER_DOWN
 endif
 
 ifeq ($(strip $(NO_USB_STARTUP_CHECK)), yes)
-    TMK_COMMON_DEFS += -DNO_USB_STARTUP_CHECK
+    OPT_DEFS += -DNO_USB_STARTUP_CHECK
 endif
 
 ifeq ($(strip $(JOYSTICK_SHARED_EP)), yes)
-    TMK_COMMON_DEFS += -DJOYSTICK_SHARED_EP
+    OPT_DEFS += -DJOYSTICK_SHARED_EP
     SHARED_EP_ENABLE = yes
 endif
 
 ifeq ($(strip $(JOYSTICK_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DJOYSTICK_ENABLE
+    OPT_DEFS += -DJOYSTICK_ENABLE
     ifeq ($(strip $(SHARED_EP_ENABLE)), yes)
-        TMK_COMMON_DEFS += -DJOYSTICK_SHARED_EP
+        OPT_DEFS += -DJOYSTICK_SHARED_EP
         SHARED_EP_ENABLE = yes
     endif
 endif
 
 ifeq ($(strip $(DIGITIZER_SHARED_EP)), yes)
-    TMK_COMMON_DEFS += -DDIGITIZER_SHARED_EP
+    OPT_DEFS += -DDIGITIZER_SHARED_EP
     SHARED_EP_ENABLE = yes
 endif
 
 ifeq ($(strip $(DIGITIZER_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DDIGITIZER_ENABLE
+    OPT_DEFS += -DDIGITIZER_ENABLE
     ifeq ($(strip $(SHARED_EP_ENABLE)), yes)
-        TMK_COMMON_DEFS += -DDIGITIZER_SHARED_EP
+        OPT_DEFS += -DDIGITIZER_SHARED_EP
         SHARED_EP_ENABLE = yes
     endif
 endif
 
 ifeq ($(strip $(SHARED_EP_ENABLE)), yes)
-    TMK_COMMON_DEFS += -DSHARED_EP_ENABLE
+    OPT_DEFS += -DSHARED_EP_ENABLE
 endif
 
 ifeq ($(strip $(USB_HID_ENABLE)), yes)