diff --git a/src/Makefile b/src/Makefile
index 9635aed..26b1cbb 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -321,7 +321,7 @@ TESTS-SOURCES=tests.scm listing.import.scm util-dict-list.import.scm	\
 tests.o: tests.import.scm
 tests.import.scm: $(TESTS-SOURCES)
 
-UTIL-PROC-SOURCES=util-proc.scm
+UTIL-PROC-SOURCES=util-proc.scm duck.import.scm
 
 util-proc.o: util-proc.import.scm
 util-proc.import.scm: $(UTIL-PROC-SOURCES)