diff --git a/Makefile b/Makefile
index 538c892..f7030c1 100644
--- a/Makefile
+++ b/Makefile
@@ -43,28 +43,49 @@ clean:
 ################################################################
 # Modules
 
-testing.o: testing.scm
-testing.import.scm: testing.scm
+brmsaptool.o: brmsaptool.scm testing.import.scm listing.import.scm	\
+	dictionary.import.scm month.import.scm period.import.scm	\
+	ansi.import.scm member-file.import.scm				\
+	command-line.import.scm
 
-listing.o: listing.scm testing.import.scm
-listing.import.scm: listing.scm testing.import.scm
+TESTING-SOURCES=testing.scm
 
-dictionary.o: dictionary.scm testing.import.scm
-dictionary.import.scm: dictionary.scm testing.import.scm
+testing.o: $(TESTING-SOURCES)
+testing.import.scm: $(TESTING-SOURCES)
 
-month.o: month.scm testing.import.scm
-month.import.scm: month.scm testing.import.scm
+LISTING-SOURCES=listing.scm testing.import.scm
 
-period.o: period.scm testing.import.scm month.import.scm
-period.import.scm: period.scm testing.import.scm month.import.scm
+listing.o: $(LISTING-SOURCES)
+listing.import.scm: $(LISTING-SOURCES)
 
-ansi.o: ansi.scm testing.import.scm
-ansi.import.scm: ansi.scm testing.import.scm
+DICTIONARY-SOURCES=dictionary.scm testing.import.scm
 
-member-file.o: member-file.scm dictionary.import.scm ansi.import.scm month.import.scm period.import.scm listing.import.scm testing.import.scm
-member-file.import.scm: member-file.scm dictionary.import.scm ansi.import.scm month.import.scm period.import.scm listing.import.scm testing.import.scm
+dictionary.o: $(DICTIONARY-SOURCES)
+dictionary.import.scm: $(DICTIONARY-SOURCES)
 
-command-line.o: command-line.scm testing.import.scm
-command-line.import.scm: command-line.scm testing.import.scm
+MONTH-SOURCES=month.scm testing.import.scm
 
-brmsaptool.o: brmsaptool.scm testing.import.scm listing.import.scm dictionary.import.scm month.import.scm period.import.scm ansi.import.scm member-file.import.scm command-line.import.scm
+month.o: $(MONTH-SOURCES)
+month.import.scm: $(MONTH-SOURCES)
+
+PERIOD-SOURCES=period.scm testing.import.scm month.import.scm
+
+period.o: $(PERIOD-SOURCES)
+period.import.scm: $(PERIOD-SOURCES)
+
+ANSI-SOURCES=ansi.scm testing.import.scm
+
+ansi.o: $(ANSI-SOURCES)
+ansi.import.scm: $(ANSI-SOURCES)
+
+MEMBER-FILE-SOURCES=member-file.scm dictionary.import.scm	\
+	ansi.import.scm month.import.scm period.import.scm	\
+	listing.import.scm testing.import.scm
+
+member-file.o: $(MEMBER-FILE-SOURCES)
+member-file.import.scm: $(MEMBER-FILE-SOURCES)
+
+COMMAND-LINE-SOURCES=command-line.scm testing.import.scm
+
+command-line.o: $(COMMAND-LINE-SOURCES)
+command-line.import.scm: $(COMMAND-LINE-SOURCES)