diff --git a/Makefile b/Makefile
index 35298d8ea39..4a4355226df 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,7 @@ ifndef CPPFLAGS
 endif
 
 ifdef FILESDIR
-    CPPFLAGS+=-DFILESDIR=\"$(FILESDIR)\"
+    override CPPFLAGS+=-DFILESDIR=\"$(FILESDIR)\"
 endif
 
 RDYNAMIC=-rdynamic
diff --git a/tools/dmake/dmake.cpp b/tools/dmake/dmake.cpp
index 49901e54cfb..f57a4f790df 100644
--- a/tools/dmake/dmake.cpp
+++ b/tools/dmake/dmake.cpp
@@ -599,7 +599,7 @@ int main(int argc, char **argv)
 
     // explicit files dir..
     fout << "ifdef FILESDIR\n"
-         << "    CPPFLAGS+=-DFILESDIR=\\\"$(FILESDIR)\\\"\n"
+         << "    override CPPFLAGS+=-DFILESDIR=\\\"$(FILESDIR)\\\"\n"
          << "endif\n\n";
 
     // enable backtrac