-SRCFILES := $(shell find . -mindepth 1 -maxdepth 3 -name "*.c")
-HDRFILES := $(shell find . -mindepth 1 -maxdepth 3 -name "*.h")
+PROJDIRS := functions includes internals
+SRCFILES := $(shell find $(PROJDIRS) -mindepth 1 -maxdepth 3 -name "*.c")
+HDRFILES := $(shell find $(PROJDIRS) -mindepth 1 -maxdepth 3 -name "*.h")
+INTFILES := atomax digits lengthmods seed strtox_main strtox_prelim rename remove _Exit