diff --git a/reproducible.patch b/reproducible.patch
new file mode 100644
index 0000000..d496efc
--- /dev/null
+++ b/reproducible.patch
@@ -0,0 +1,53 @@
+Author: Bernhard M. Wiedemann <bwiedemann suse de>
+To: Phil Budne <phil@regressive.org>
+CC: <fred_weigel@hotmail.com>
+Subject: [Patch] PoC reproducible builds
+
+Allow for bit-identical binaries to be created
+See https://reproducible-builds.org/ for why.
+
+This patch was done while working on reproducible builds for openSUSE.
+
+Index: snobol4-2.3.1/snolib/setuputil.sno
+===================================================================
+--- snobol4-2.3.1.orig/snolib/setuputil.sno
++++ snobol4-2.3.1/snolib/setuputil.sno
+@@ -194,7 +194,7 @@ setup.makeinclude
+ +	ou = IO_FINDUNIT()
+ 	of = setup.sno(t)
+ 	OUTPUT(.out, ou,, of)			:f(freturn)
+-	out = "* Generated by setuputil.sno setup.makeinclude() " DATE()
++	out = "* Generated by setuputil.sno setup.makeinclude() "
+ 	modname = REPLACE(t['module'], &LCASE, &UCASE) '_DL'
+ 	out = setup.t modname ' = "' t['module'] '"'
+ 	iu = IO_FINDUNIT()
+Index: snobol4-2.3.1/configure
+===================================================================
+--- snobol4-2.3.1.orig/configure
++++ snobol4-2.3.1/configure
+@@ -45,6 +45,10 @@ DATE=`date`
+ 
+ # run hostname from subshell to redirect shell "not found message"
+ HOST=`(hostname) 2>/dev/null || uname -n`
++if [ -n "$SOURCE_DATE_EPOCH" ] ; then
++    DATE='reproducible'
++    HOST='reproducible'
++fi
+ 
+ VERSION_H=version.h.tmp
+ CONFIG_H=config.h.tmp
+Index: snobol4-2.3.1/Makefile2.m4
+===================================================================
+--- snobol4-2.3.1.orig/Makefile2.m4
++++ snobol4-2.3.1/Makefile2.m4
+@@ -260,8 +260,8 @@ build.o: always
+ 	echo '/* MACHINE GENERATED.  EDITING IS FUTILE */'	> build.c
+ 	echo '#include "h.h"'					>> build.c
+ 	echo 'const char build_files[] = "'$(SRCS)'";'		>> build.c
+-	echo 'const char build_date[] = "'`date`'";'		>> build.c
+-	echo 'const char build_dir[] = "'`pwd`'";'		>> build.c
++	echo 'const char build_date[] = "'nodate'";'		>> build.c
++	echo 'const char build_dir[] = "'reproducible'";'	>> build.c
+ 	$(CC) $(CFLAGS) -c build.c
+ changequote([,])dnl
+ 
diff --git a/snobol4.changes b/snobol4.changes
index ab60832..30e383a 100644
--- a/snobol4.changes
+++ b/snobol4.changes
@@ -1,3 +1,8 @@
+-------------------------------------------------------------------
+Mon May 29 14:29:04 UTC 2023 - Bernhard Wiedemann <bwiedemann@suse.com>
+
+- Add reproducible.patch to drop build date (boo#1047218)
+
 -------------------------------------------------------------------
 Tue Apr  4 08:29:44 UTC 2023 - Dominique Leuenberger <dimstar@opensuse.org>
 
diff --git a/snobol4.spec b/snobol4.spec
index 3bab4ba..33f2a57 100644
--- a/snobol4.spec
+++ b/snobol4.spec
@@ -27,6 +27,7 @@ URL:            https://www.regressive.org/snobol4/csnobol4/curr/
 Source0:        https://ftp.regressive.org/snobol4/%{name}-%{version}.tar.gz
 # Do not hardcode -O3.
 Patch1:         snobol4-2.3.1-configure-no-opt.patch
+Patch2:         reproducible.patch
 BuildRequires:  gcc
 BuildRequires:  gcc-c++
 BuildRequires:  gdbm-devel