diff --git a/tmk_core/rules.mk b/tmk_core/rules.mk
index 1c33cc84..b559e57b 100644
--- a/tmk_core/rules.mk
+++ b/tmk_core/rules.mk
@@ -348,9 +348,9 @@ GENDEPFLAGS = -MMD -MP -MF .dep/$(subst /,_,$@).d
 # Combine all necessary flags and optional flags.
 # Add target processor to flags.
 # You can give extra flags at 'make' command line like: make EXTRAFLAGS=-DFOO=bar
-ALL_CFLAGS = -mmcu=$(MCU) $(CFLAGS) $(GENDEPFLAGS) $(EXTRAFLAGS)
-ALL_CPPFLAGS = -mmcu=$(MCU) -x c++ $(CPPFLAGS) $(GENDEPFLAGS) $(EXTRAFLAGS)
-ALL_ASFLAGS = -mmcu=$(MCU) -x assembler-with-cpp $(ASFLAGS) $(EXTRAFLAGS)
+ALL_CFLAGS = -mmcu=$(MCU) $(CFLAGS) $(GENDEPFLAGS) $(EXTRAFLAGS) $(EXTRACFLAGS)
+ALL_CPPFLAGS = -mmcu=$(MCU) -x c++ $(CPPFLAGS) $(GENDEPFLAGS) $(EXTRAFLAGS) $(EXTRACPPFLAGS)
+ALL_ASFLAGS = -mmcu=$(MCU) -x assembler-with-cpp $(ASFLAGS) $(EXTRAFLAGS) $(EXTRAASFLAGS)