diff --git a/Makefile b/Makefile
index e3671d582..a8709f914 100644
--- a/Makefile
+++ b/Makefile
@@ -50,7 +50,7 @@ crystal11:  pokecrystal11.gbc
 crystal-au: pokecrystal-au.gbc
 
 clean:
-	rm -f $(roms) $(crystal_obj) $(crystal11_obj) $(crystal_au_obj) $(roms:.gbc=.map) $(roms:.gbc=.sym)
+	rm -f $(roms) $(crystal_obj) $(crystal11_obj) $(crystal_au_obj) $(roms:.gbc=.map) $(roms:.gbc=.sym) rgbdscheck.o
 	find gfx \( -name "*.[12]bpp" -o -name "*.lz" -o -name "*.gbcpal" -o -name "*.sgb.tilemap" \) -delete
 	find gfx/pokemon -mindepth 1 ! -path "gfx/pokemon/unown/*" \( -name "bitmask.asm" -o -name "frames.asm" -o -name "front.animated.tilemap" -o -name "front.dimensions" \) -delete
 	$(MAKE) clean -C tools/
@@ -71,11 +71,14 @@ $(crystal_obj):    RGBASMFLAGS +=
 $(crystal11_obj):  RGBASMFLAGS += -D _CRYSTAL11
 $(crystal_au_obj): RGBASMFLAGS += -D _CRYSTAL11 -D _CRYSTAL_AU
 
+rgbdscheck.o: rgbdscheck.asm
+	$(RGMASM) -o $@ $<
+
 # The dep rules have to be explicit or else missing files won't be reported.
 # As a side effect, they're evaluated immediately instead of when the rule is invoked.
 # It doesn't look like $(shell) can be deferred so there might not be a better way.
 define DEP
-$1: $2 $$(shell tools/scan_includes $2)
+$1: $2 $$(shell tools/scan_includes $2) | rgbdscheck.o
 	$$(RGBASM) $$(RGBASMFLAGS) -o $$@ $$<
 endef
 
diff --git a/constants.asm b/constants.asm
index 758b3abcc..7864ec9d0 100644
--- a/constants.asm
+++ b/constants.asm
@@ -1,7 +1,3 @@
-if __RGBDS_MAJOR__ <= 0 && __RGBDS_MINOR__ < 4
-	fail "pokecrystal requires rgbds 0.4.0 or newer."
-endc
-
 INCLUDE "charmap.asm"
 
 INCLUDE "macros.asm"
diff --git a/rgbdscheck.asm b/rgbdscheck.asm
new file mode 100644
index 000000000..d5e2e5011
--- /dev/null
+++ b/rgbdscheck.asm
@@ -0,0 +1,12 @@
+; pokecrystal requires rgbds 0.4.0 or newer.
+MAJOR EQU 0
+MINOR EQU 4
+PATCH EQU 0
+
+if !DEF(__RGBDS_MAJOR__) || !DEF(__RGBDS_MINOR__) || !DEF(__RGBDS_PATCH__)
+	fail "pokecrystal requires rgbds {MAJOR}.{MINOR}.{PATCH} or newer."
+elif (__RGBDS_MAJOR__ < MAJOR) || \
+	(__RGBDS_MAJOR__ == MAJOR && __RGBDS_MINOR__ < MINOR) || \
+	(__RGBDS_MAJOR__ == MAJOR && __RGBDS_MINOR__ == MINOR && __RGBDS_PATCH__ < PATCH)
+	fail "pokecrystal requires rgbds {MAJOR}.{MINOR}.{PATCH} or newer."
+endc