diff --git a/Makefile b/Makefile
index 0035eb626..1d16a7f29 100644
--- a/Makefile
+++ b/Makefile
@@ -136,6 +136,10 @@ C_ASM_OBJS := $(patsubst $(C_SUBDIR)/%.s,$(C_BUILDDIR)/%.o,$(C_ASM_SRCS))
 ASM_SRCS := $(wildcard $(ASM_SUBDIR)/*.s)
 ASM_OBJS := $(patsubst $(ASM_SUBDIR)/%.s,$(ASM_BUILDDIR)/%.o,$(ASM_SRCS))
 
+# get all the data/*.s files EXCEPT the ones with specific rules
+REGULAR_DATA_ASM_SRCS := $(wildcard $(DATA_ASM_SUBDIR)/*.s)
+REGULAR_DATA_ASM_SRCS := $(filter-out $(DATA_ASM_SUBDIR)/maps.s $(DATA_ASM_SUBDIR)/map_events.s, $(REGULAR_DATA_ASM_SRCS))
+
 DATA_ASM_SRCS := $(wildcard $(DATA_ASM_SUBDIR)/*.s)
 DATA_ASM_OBJS := $(patsubst $(DATA_ASM_SUBDIR)/%.s,$(DATA_ASM_BUILDDIR)/%.o,$(DATA_ASM_SRCS))
 
@@ -275,23 +279,32 @@ endif
 $(C_BUILDDIR)/%.o: $(C_SUBDIR)/%.s $$(c_asm_dep)
 	$(AS) $(ASFLAGS) -o $@ $<
 
-ifeq ($(NODEP),1)
-$(ASM_BUILDDIR)/%.o: asm_dep :=
-else
-$(ASM_BUILDDIR)/%.o: asm_dep = $(shell $(SCANINC) -I "" $(ASM_SUBDIR)/$*.s)
-endif
+# 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.
 
-$(ASM_BUILDDIR)/%.o: $(ASM_SUBDIR)/%.s $$(asm_dep)
+
+ifeq ($(NODEP),1)
+$(ASM_BUILDDIR)/%.o: $(ASM_SUBDIR)/%.s
 	$(AS) $(ASFLAGS) -o $@ $<
-
-ifeq ($(NODEP),1)
-$(DATA_ASM_BUILDDIR)/%.o: data_dep :=
 else
-$(DATA_ASM_BUILDDIR)/%.o: data_dep = $(shell $(SCANINC) -I include -I "" $(DATA_ASM_SUBDIR)/$*.s)
+define ASM_DEP
+$1: $2 $$(shell $(SCANINC) -I include -I "" $2)
+	$$(AS) $$(ASFLAGS) -o $$@ $$<
+endef
+$(foreach src, $(ASM_SRCS), $(eval $(call ASM_DEP,$(patsubst $(ASM_SUBDIR)/%.s,$(ASM_BUILDDIR)/%.o, $(src)),$(src))))
 endif
 
-$(DATA_ASM_BUILDDIR)/%.o: $(DATA_ASM_SUBDIR)/%.s $$(data_dep)
+ifeq ($(NODEP),1)
+$(DATA_ASM_BUILDDIR)/%.o: $(DATA_ASM_SUBDIR)/%.s
 	$(PREPROC) $< charmap.txt | $(CPP) -I include | $(AS) $(ASFLAGS) -o $@
+else
+define DATA_ASM_DEP
+$1: $2 $$(shell $(SCANINC) -I include -I "" $2)
+	$$(PREPROC) $$< charmap.txt | $$(CPP) -I include | $$(AS) $$(ASFLAGS) -o $$@
+endef
+$(foreach src, $(REGULAR_DATA_ASM_SRCS), $(eval $(call DATA_ASM_DEP,$(patsubst $(DATA_ASM_SUBDIR)/%.s,$(DATA_ASM_BUILDDIR)/%.o, $(src)),$(src))))
+endif
 
 $(SONG_BUILDDIR)/%.o: $(SONG_SUBDIR)/%.s
 	$(AS) $(ASFLAGS) -I sound -o $@ $<
diff --git a/tools/scaninc/scaninc.cpp b/tools/scaninc/scaninc.cpp
index a3e40c5d9..dcb16c0e7 100644
--- a/tools/scaninc/scaninc.cpp
+++ b/tools/scaninc/scaninc.cpp
@@ -108,7 +108,7 @@ int main(int argc, char **argv)
                     break;
                 }
             }
-            if (!exists && file.FileType() == SourceFileType::Asm)
+            if (!exists && (file.FileType() == SourceFileType::Asm || file.FileType() == SourceFileType::Inc))
             {
                 path = include;
             }