Use $? instead of $< in implicit rules.

@@ -5,7 +5,7 @@
 bin_SCRIPTS = sieve.scm
 
 sieve.scm: sieve.scm.in
-	sed "s,%GUILE_BINDIR%,@GUILE_BINDIR@,g;s,%BINDIR%,$(bindir),g;s,%LIBDIR%,$(pkgdatadir),g;s,%PACKAGE%,$(PACKAGE),g;s,%VERSION%,$(VERSION),g" $< > $@
+	sed "s,%GUILE_BINDIR%,@GUILE_BINDIR@,g;s,%BINDIR%,$(bindir),g;s,%LIBDIR%,$(pkgdatadir),g;s,%PACKAGE%,$(PACKAGE),g;s,%VERSION%,$(VERSION),g" $? > $@
 
 CLEANFILES = sieve.scm
 

@@ -59,7 +59,7 @@ guile-procedures.txt: $(DOT_DOC_FILES)
 
 mailutils.scm: mailutils.scm.in $(libmu_scm_la_SOURCES:.c=.inc)
 	m4 -DVERSION=$(VERSION) -DLIBDIR=$(libdir) \
-           -DBUILDDIR=$(top_builddir)/libmu_scm $< > $@
+           -DBUILDDIR=$(top_builddir)/libmu_scm $? > $@
 
 
 ## Add -MG to make the .x magic work with auto-dep code.