diff --git a/unittest/Makefile.am b/unittest/Makefile.am
index fd7530ee262..bfa9f40f8ce 100644
--- a/unittest/Makefile.am
+++ b/unittest/Makefile.am
@@ -23,5 +23,5 @@ examples:
 	cd examples && $(MAKE)
 
 unit: $(srcdir)/unit.pl
-	cp $< $@
+	cp $(srcdir)/unit.pl $@
 	chmod +x $@