--- kawa-3.1.1/Makefile.in	2024-09-24 08:20:55.039208179 +0200
+++ kawa-3.1.1/Makefile.in	2024-09-24 08:24:48.547467028 +0200
@@ -1889,11 +1889,13 @@
 
 lib/kawa.jar: ./kawa-jar.stamp $(META_INF_FILES) classes.list
 	mkdir -p lib
-	$(JAR) cmf $(srcdir)/jar-manifest $@ $(META_INF_FILES) @classes.list
+	$(JAR) --date="$$(date -u -d @$${SOURCE_DATE_EPOCH:-$$(date +%s)} +%Y-%m-%dT%H:%M:%SZ)" \
+		--create --manifest=$(srcdir)/jar-manifest --file=$@ $(META_INF_FILES) @classes.list
 
 lib/kawart.jar: ./kawa-jar.stamp classes-rt.list
 	mkdir -p lib
-	$(JAR) cf $@ @classes-rt.list
+	$(JAR) --date="$$(date -u -d @$${SOURCE_DATE_EPOCH:-$$(date +%s)} +%Y-%m-%dT%H:%M:%SZ)" \
+		--create --file=$@ @classes-rt.list
 
 $(META_ScriptEngineFactory): Makefile
 	echo 'kawa.standard.SchemeScriptEngineFactory #Scheme' >tmp.ScriptEngineFactory
@@ -1958,14 +1960,20 @@
 	  && cd tmpdir \
 	  && $$srcdir/configure --with-swing \
 	  && $(MAKE) \
-	  && $(JAR) cmf $$srcdir/gnu/jemacs/jar-manifest \
-	      ../lib/jemacs.jar \
+	  && $(JAR) \
+	      --date="$$(date -u -d @$${SOURCE_DATE_EPOCH:-$$(date +%s)} +%Y-%m-%dT%H:%M:%SZ)" \
+	      --create \
+	      --manifest=$$srcdir/gnu/jemacs/jar-manifest \
+	      --file=../lib/jemacs.jar \
 	      `$(FIND) . -name '*.class' -print` \
 	  && cd .. && rm -rf tmpdir
 
 lib/bytecode.jar: ./gnu/bytecode/java-classes.stamp
-	$(JAR) cmf $(srcdir)/gnu/bytecode/jar-manifest \
-	  lib/bytecode.jar \
+	$(JAR) \
+	  --date="$$(date -u -d @$${SOURCE_DATE_EPOCH:-$$(date +%s)} +%Y-%m-%dT%H:%M:%SZ)" \
+	  --create \
+	  --manifest=$(srcdir)/gnu/bytecode/jar-manifest \
+	  --file=lib/bytecode.jar \
 	  `$(FIND) gnu/bytecode -name '*.class' -print` 
 
 kawa-@VERSION@-src.zip: kawa-@VERSION@.tar.gz