diff --git a/Makefile b/Makefile
index e5b35a8302..1bfeebf616 100644
--- a/Makefile
+++ b/Makefile
@@ -159,7 +159,7 @@ $(C_BUILDDIR)/%.o : $(C_SUBDIR)/%.c $$(c_dep)
 ifeq ($(NODEP),1)
 $(ASM_BUILDDIR)/%.o: asm_dep :=
 else
-$(ASM_BUILDDIR)/%.o: asm_dep = $(shell $(SCANINC) $(ASM_SUBDIR)/$*.s)
+$(ASM_BUILDDIR)/%.o: asm_dep = $(shell $(SCANINC) -I "" $(ASM_SUBDIR)/$*.s)
 endif
 
 $(ASM_BUILDDIR)/%.o: $(ASM_SUBDIR)/%.s $$(asm_dep)
@@ -168,7 +168,7 @@ $(ASM_BUILDDIR)/%.o: $(ASM_SUBDIR)/%.s $$(asm_dep)
 ifeq ($(NODEP),1)
 $(DATA_ASM_BUILDDIR)/%.o: data_dep :=
 else
-$(DATA_ASM_BUILDDIR)/%.o: data_dep = $(shell $(SCANINC) -I include $(DATA_ASM_SUBDIR)/$*.s)
+$(DATA_ASM_BUILDDIR)/%.o: data_dep = $(shell $(SCANINC) -I include -I "" $(DATA_ASM_SUBDIR)/$*.s)
 endif
 
 $(DATA_ASM_BUILDDIR)/%.o: $(DATA_ASM_SUBDIR)/%.s $$(data_dep)
diff --git a/tools/scaninc/scaninc.cpp b/tools/scaninc/scaninc.cpp
index 0d55d11f65..696842dc91 100644
--- a/tools/scaninc/scaninc.cpp
+++ b/tools/scaninc/scaninc.cpp
@@ -62,7 +62,7 @@ int main(int argc, char **argv)
                 argv++;
                 includeDir = std::string(argv[0]);
             }
-            if (includeDir.back() != '/')
+            if (!includeDir.empty() && includeDir.back() != '/')
             {
                 includeDir += '/';
             }