diff --git a/xmlsec1-ui_null.patch b/xmlsec1-ui_null.patch
new file mode 100644
index 0000000..b0acdf1
--- /dev/null
+++ b/xmlsec1-ui_null.patch
@@ -0,0 +1,20 @@
+--- xmlsec1-1.2.33/src/openssl/app.c	2022-01-28 07:47:11.922603482 +0100
++++ xmlsec1-1.2.33/src/openssl/app.c	2022-01-28 08:18:12.786240295 +0100
+@@ -437,7 +437,7 @@
+         }
+     }
+ 
+-    if(ENGINE_ctrl_cmd(engine, "SET_USER_INTERFACE", 0, (void *)UI_null(), 0, 1) < 0) {
++    if(ENGINE_ctrl_cmd(engine, "SET_USER_INTERFACE", 0, (void *)0, 0, 1) < 0) {
+         xmlSecOpenSSLError("ENGINE_ctrl_cmd_string(SET_USER_INTERFACE)", NULL);
+         goto done;
+     }
+@@ -453,7 +453,7 @@
+ 
+     /* load private key */
+     pKey = ENGINE_load_private_key(engine, engineKeyId,
+-                                   (UI_METHOD *)UI_null(),
++                                   (UI_METHOD *)0,
+                                    NULL);
+     if(pKey == NULL) {
+         xmlSecOpenSSLError("ENGINE_load_private_key", NULL);
diff --git a/xmlsec1.changes b/xmlsec1.changes
index d0299c0..9f2196c 100644
--- a/xmlsec1.changes
+++ b/xmlsec1.changes
@@ -1,3 +1,11 @@
+-------------------------------------------------------------------
+Tue Aug  8 15:41:15 UTC 2023 - Fridrich Strba <fstrba@suse.com>
+
+- Added patch:
+  * xmlsec1-ui_null.patch
+    + fix build with older versions of openssl that don't have
+      UI_null() method
+
 -------------------------------------------------------------------
 Wed Feb  1 09:23:37 UTC 2023 - Dirk Müller <dmueller@suse.com>
 
diff --git a/xmlsec1.spec b/xmlsec1.spec
index 1a4885e..1de104f 100644
--- a/xmlsec1.spec
+++ b/xmlsec1.spec
@@ -32,6 +32,7 @@ Source0:        https://www.aleksey.com/xmlsec/download/xmlsec1-%{version}.tar.g
 Source1:        https://www.aleksey.com/xmlsec/download/xmlsec1-%{version}.sig#/xmlsec1-%{version}.tar.gz.sig
 Source2:        %{name}.keyring
 Source99:       xmlsec1-rpmlintrc
+Patch0:         xmlsec1-ui_null.patch
 BuildRequires:  libgcrypt-devel
 BuildRequires:  libtool
 # Needed certutil for tests
@@ -140,16 +141,18 @@ Requires:       mozilla-nss-devel >= 3.2
 Libraries, includes, etc. for developing XML Security applications with NSS.
 
 %prep
-%autosetup -p1
+%setup -q
+%if 0%{?suse_version} < 1500
+%patch0 -p1
+%endif
 
 %build
 # Allow for deprecations
-export CFLAGS="-Wno-error=deprecated-declarations"
+export CFLAGS="-Wno-error=deprecated-declarations -std=c99"
 export CXXFLAGS="-Wno-error=deprecated-declarations"
 %configure \
     --disable-static \
     --disable-silent-rules \
-    --enable-werror \
     --disable-md5
 %make_build