diff --git a/dev-db/postgresql/files/postgresql-16-xml-2.12.patch b/dev-db/postgresql/files/postgresql-16-xml-2.12.patch
new file mode 100644
index 0000000..aac072c
--- /dev/null
+++ b/dev-db/postgresql/files/postgresql-16-xml-2.12.patch
@@ -0,0 +1,83 @@
+From e02fea093ebb7ff5093c4cd9827710000bb31146 Mon Sep 17 00:00:00 2001
+From: Tom Lane <tgl@sss.pgh.pa.us>
+Date: Mon, 29 Jan 2024 12:06:07 -0500
+Subject: [PATCH] Fix incompatibilities with libxml2 >= 2.12.0.
+
+libxml2 changed the required signature of error handler callbacks
+to make the passed xmlError struct "const".  This is causing build
+failures on buildfarm member caiman, and no doubt will start showing
+up in the field quite soon.  Add a version check to adjust the
+declaration of xml_errorHandler() according to LIBXML_VERSION.
+
+2.12.x also produces deprecation warnings for contrib/xml2/xpath.c's
+assignment to xmlLoadExtDtdDefaultValue.  I see no good reason for
+that to still be there, seeing that we disabled external DTDs (at a
+lower level) years ago for security reasons.  Let's just remove it.
+
+Back-patch to all supported branches, since they might all get built
+with newer libxml2 once it gets a bit more popular.  (The back
+branches produce another deprecation warning about xpath.c's use of
+xmlSubstituteEntitiesDefault().  We ought to consider whether to
+back-patch all or part of commit 65c5864d7 to silence that.  It's
+less urgent though, since it won't break the buildfarm.)
+
+Discussion: https://postgr.es/m/1389505.1706382262@sss.pgh.pa.us
+---
+ contrib/xml2/xpath.c        |  1 -
+ src/backend/utils/adt/xml.c | 14 ++++++++++++--
+ 2 files changed, 12 insertions(+), 3 deletions(-)
+
+diff --git a/contrib/xml2/xpath.c b/contrib/xml2/xpath.c
+index a692dc6be8..94641930f7 100644
+--- a/contrib/xml2/xpath.c
++++ b/contrib/xml2/xpath.c
+@@ -75,7 +75,6 @@ pgxml_parser_init(PgXmlStrictness strictness)
+ 	xmlInitParser();
+ 
+ 	xmlSubstituteEntitiesDefault(1);
+-	xmlLoadExtDtdDefaultValue = 1;
+ 
+ 	return xmlerrcxt;
+ }
+diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
+index 2300c7ebf3..9f4e775003 100644
+--- a/src/backend/utils/adt/xml.c
++++ b/src/backend/utils/adt/xml.c
+@@ -66,6 +66,16 @@
+ #if LIBXML_VERSION >= 20704
+ #define HAVE_XMLSTRUCTUREDERRORCONTEXT 1
+ #endif
++
++/*
++ * libxml2 2.12 decided to insert "const" into the error handler API.
++ */
++#if LIBXML_VERSION >= 21200
++#define PgXmlErrorPtr const xmlError *
++#else
++#define PgXmlErrorPtr xmlErrorPtr
++#endif
++
+ #endif							/* USE_LIBXML */
+ 
+ #include "access/htup_details.h"
+@@ -123,7 +133,7 @@ static xmlParserInputPtr xmlPgEntityLoader(const char *URL, const char *ID,
+ 										   xmlParserCtxtPtr ctxt);
+ static void xml_errsave(Node *escontext, PgXmlErrorContext *errcxt,
+ 						int sqlcode, const char *msg);
+-static void xml_errorHandler(void *data, xmlErrorPtr error);
++static void xml_errorHandler(void *data, PgXmlErrorPtr error);
+ static int	errdetail_for_xml_code(int code);
+ static void chopStringInfoNewlines(StringInfo str);
+ static void appendStringInfoLineSeparator(StringInfo str);
+@@ -2002,7 +2012,7 @@ xml_errsave(Node *escontext, PgXmlErrorContext *errcxt,
+  * Error handler for libxml errors and warnings
+  */
+ static void
+-xml_errorHandler(void *data, xmlErrorPtr error)
++xml_errorHandler(void *data, PgXmlErrorPtr error)
+ {
+ 	PgXmlErrorContext *xmlerrcxt = (PgXmlErrorContext *) data;
+ 	xmlParserCtxtPtr ctxt = (xmlParserCtxtPtr) error->ctxt;
+-- 
+2.30.2
+
diff --git a/dev-db/postgresql/postgresql-16.1-r1.ebuild b/dev-db/postgresql/postgresql-16.1-r2.ebuild
similarity index 98%
rename from dev-db/postgresql/postgresql-16.1-r1.ebuild
rename to dev-db/postgresql/postgresql-16.1-r2.ebuild
index c563a2a..79a1a04 100644
--- a/dev-db/postgresql/postgresql-16.1-r1.ebuild
+++ b/dev-db/postgresql/postgresql-16.1-r2.ebuild
@@ -48,7 +48,10 @@ readline? ( sys-libs/readline:0= )
 server? ( systemd? ( sys-apps/systemd ) )
 ssl? ( >=dev-libs/openssl-0.9.6-r1:0= )
 tcl? ( >=dev-lang/tcl-8:0= )
-xml? ( dev-libs/libxml2 dev-libs/libxslt )
+xml? (
+	 >=dev-libs/libxml2-2.12.0
+	 dev-libs/libxslt
+)
 zlib? ( sys-libs/zlib )
 zstd? ( app-arch/zstd )
 "
@@ -111,7 +114,8 @@ src_prepare() {
 			die 'PGSQL_PAM_SERVICE rename failed.'
 	fi
 
-	eapply "${FILESDIR}"/postgresql-16-openssl3.2.patch
+	eapply "${FILESDIR}"/postgresql-16-openssl3.2.patch \
+		   "${FILESDIR}"/postgresql-${SLOT}-xml-2.12.patch
 
 	eapply_user
 }