diff --git a/0001-Do-not-try-to-store-negative-values-in-unsigned-int.patch b/0001-Do-not-try-to-store-negative-values-in-unsigned-int.patch
new file mode 100644
index 0000000..360acf3
--- /dev/null
+++ b/0001-Do-not-try-to-store-negative-values-in-unsigned-int.patch
@@ -0,0 +1,28 @@
+From bb5eec59e3ec66f6dccb79b1900aa806a1cca12e Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Tom=C3=A1=C5=A1=20Chv=C3=A1tal?= <tchvatal@suse.com>
+Date: Fri, 8 Dec 2017 14:59:08 +0100
+Subject: [PATCH] Do not try to store negative values in unsigned int
+
+---
+ deflate.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+diff --git a/deflate.c b/deflate.c
+index 1ec7614..1bad1eb 100644
+--- a/deflate.c
++++ b/deflate.c
+@@ -1536,7 +1536,10 @@ local void fill_window(s)
+ 
+         /* Initialize the hash value now that we have some input: */
+         if (s->lookahead + s->insert >= MIN_MATCH) {
+-            uInt str = s->strstart - s->insert;
++            uInt str = 0;
++            /* storing negative values to uInt is not good idea */
++            if (s->strstart - s->insert > 0)
++                str = s->strstart - s->insert;
+             s->ins_h = s->window[str];
+             UPDATE_HASH(s, s->ins_h, s->window[str + 1]);
+ #if MIN_MATCH != 3
+-- 
+2.15.1
+
diff --git a/zlib.changes b/zlib.changes
index de5473c..18af36a 100644
--- a/zlib.changes
+++ b/zlib.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Tue May 15 10:56:20 UTC 2018 - tchvatal@suse.com
+
+- Add patch to safeguard against negative values in uInt bsc#1071321:
+  * 0001-Do-not-try-to-store-negative-values-in-unsigned-int.patch
+
 -------------------------------------------------------------------
 Mon Jun 12 17:35:18 UTC 2017 - kah0922@gmail.com
 
diff --git a/zlib.spec b/zlib.spec
index 3f55e3d..fbdc16a 100644
--- a/zlib.spec
+++ b/zlib.spec
@@ -33,6 +33,8 @@ Source6:        zlib-rpmlintrc
 Patch0:         zlib-1.2.11-optimized-s390.patch
 #PATCH-FIX-SUSE: compiler check of varguments passed to gzprintf
 Patch1:         zlib-format.patch
+#PATCH-FIX-UPSTREAM do not store negative values in uInt
+Patch2:         0001-Do-not-try-to-store-negative-values-in-unsigned-int.patch
 BuildRequires:  autoconf
 BuildRequires:  automake
 BuildRequires:  libtool
@@ -115,6 +117,7 @@ developing applications which use minizip.
 %setup -q
 %patch0
 %patch1
+%patch2 -p1
 
 %build
 export LDFLAGS="-Wl,-z,relro,-z,now"