diff --git a/postgresql-timetz.patch b/postgresql-timetz.patch
new file mode 100644
index 0000000..1337335
--- /dev/null
+++ b/postgresql-timetz.patch
@@ -0,0 +1,109 @@
+From: Tom Lane <tgl@sss.pgh.pa.us>
+Date: Thu, 29 Oct 2020 19:28:14 +0000 (-0400)
+Subject: Stabilize timetz test across DST transitions.
+X-Git-Url: http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff_plain;h=4a071afbd056282746a5bc9362e87f579a56402d;hp=f90149e6285aaae6b48559afce1bd638ee26c33e
+
+Stabilize timetz test across DST transitions.
+
+The timetz test cases I added in commit a9632830b were unintentionally
+sensitive to whether or not DST is active in the PST8PDT time zone.
+Thus, they'll start failing this coming weekend, as reported by
+Bernhard M. Wiedemann in bug #16689.  Fortunately, DST-awareness is
+not significant to the purpose of these test cases, so we can just
+force them all to PDT (DST hours) to preserve stability of the
+results.
+
+Back-patch to v10, as the prior patch was.
+
+Discussion: https://postgr.es/m/16689-57701daa23b377bf@postgresql.org
+---
+
+--- src/test/regress/expected/timetz.out.orig
++++ src/test/regress/expected/timetz.out
+@@ -91,45 +91,45 @@ SELECT f1 AS "Ten" FROM TIMETZ_TBL WHERE
+ (12 rows)
+ 
+ -- Check edge cases
+-SELECT '23:59:59.999999'::timetz;
++SELECT '23:59:59.999999 PDT'::timetz;
+        timetz       
+ --------------------
+  23:59:59.999999-07
+ (1 row)
+ 
+-SELECT '23:59:59.9999999'::timetz;  -- rounds up
++SELECT '23:59:59.9999999 PDT'::timetz;  -- rounds up
+    timetz    
+ -------------
+  24:00:00-07
+ (1 row)
+ 
+-SELECT '23:59:60'::timetz;  -- rounds up
++SELECT '23:59:60 PDT'::timetz;  -- rounds up
+    timetz    
+ -------------
+  24:00:00-07
+ (1 row)
+ 
+-SELECT '24:00:00'::timetz;  -- allowed
++SELECT '24:00:00 PDT'::timetz;  -- allowed
+    timetz    
+ -------------
+  24:00:00-07
+ (1 row)
+ 
+-SELECT '24:00:00.01'::timetz;  -- not allowed
+-ERROR:  date/time field value out of range: "24:00:00.01"
+-LINE 1: SELECT '24:00:00.01'::timetz;
++SELECT '24:00:00.01 PDT'::timetz;  -- not allowed
++ERROR:  date/time field value out of range: "24:00:00.01 PDT"
++LINE 1: SELECT '24:00:00.01 PDT'::timetz;
+                ^
+-SELECT '23:59:60.01'::timetz;  -- not allowed
+-ERROR:  date/time field value out of range: "23:59:60.01"
+-LINE 1: SELECT '23:59:60.01'::timetz;
++SELECT '23:59:60.01 PDT'::timetz;  -- not allowed
++ERROR:  date/time field value out of range: "23:59:60.01 PDT"
++LINE 1: SELECT '23:59:60.01 PDT'::timetz;
+                ^
+-SELECT '24:01:00'::timetz;  -- not allowed
+-ERROR:  date/time field value out of range: "24:01:00"
+-LINE 1: SELECT '24:01:00'::timetz;
++SELECT '24:01:00 PDT'::timetz;  -- not allowed
++ERROR:  date/time field value out of range: "24:01:00 PDT"
++LINE 1: SELECT '24:01:00 PDT'::timetz;
+                ^
+-SELECT '25:00:00'::timetz;  -- not allowed
+-ERROR:  date/time field value out of range: "25:00:00"
+-LINE 1: SELECT '25:00:00'::timetz;
++SELECT '25:00:00 PDT'::timetz;  -- not allowed
++ERROR:  date/time field value out of range: "25:00:00 PDT"
++LINE 1: SELECT '25:00:00 PDT'::timetz;
+                ^
+ --
+ -- TIME simple math
+--- src/test/regress/sql/timetz.sql.orig
++++ src/test/regress/sql/timetz.sql
+@@ -36,14 +36,14 @@ SELECT f1 AS "None" FROM TIMETZ_TBL WHER
+ SELECT f1 AS "Ten" FROM TIMETZ_TBL WHERE f1 >= '00:00-07';
+ 
+ -- Check edge cases
+-SELECT '23:59:59.999999'::timetz;
+-SELECT '23:59:59.9999999'::timetz;  -- rounds up
+-SELECT '23:59:60'::timetz;  -- rounds up
+-SELECT '24:00:00'::timetz;  -- allowed
+-SELECT '24:00:00.01'::timetz;  -- not allowed
+-SELECT '23:59:60.01'::timetz;  -- not allowed
+-SELECT '24:01:00'::timetz;  -- not allowed
+-SELECT '25:00:00'::timetz;  -- not allowed
++SELECT '23:59:59.999999 PDT'::timetz;
++SELECT '23:59:59.9999999 PDT'::timetz;  -- rounds up
++SELECT '23:59:60 PDT'::timetz;  -- rounds up
++SELECT '24:00:00 PDT'::timetz;  -- allowed
++SELECT '24:00:00.01 PDT'::timetz;  -- not allowed
++SELECT '23:59:60.01 PDT'::timetz;  -- not allowed
++SELECT '24:01:00 PDT'::timetz;  -- not allowed
++SELECT '25:00:00 PDT'::timetz;  -- not allowed
+ 
+ --
+ -- TIME simple math
diff --git a/postgresql12.changes b/postgresql12.changes
index 6156b95..05b0536 100644
--- a/postgresql12.changes
+++ b/postgresql12.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Tue Nov  3 13:54:38 UTC 2020 - Reinhard Max <max@suse.com>
+
+- Fix a DST problem in the test suite: postgresql-timetz.patch
+  https://postgr.es/m/16689-57701daa23b377bf@postgresql.org
+
 -------------------------------------------------------------------
 Fri Sep 25 07:34:28 UTC 2020 - Reinhard Max <max@suse.com>
 
diff --git a/postgresql12.spec b/postgresql12.spec
index 1809509..4c658c1 100644
--- a/postgresql12.spec
+++ b/postgresql12.spec
@@ -141,6 +141,7 @@ Patch4:         postgresql-plperl-keep-rpath.patch
 Patch6:         postgresql-testsuite-int8.sql.patch
 Patch8:         postgresql-testsuite-keep-results-file.patch
 Patch9:         postgresql-var-run-socket.patch
+Patch10:        postgresql-timetz.patch
 URL:            https://www.postgresql.org/
 BuildRoot:      %{_tmppath}/%{name}-%{version}-build
 Provides:       postgresql = %version-%release
@@ -448,6 +449,7 @@ touch -r configure tmp
 %patch6
 %patch8 -p1
 %patch9
+%patch10
 touch -r tmp configure
 rm tmp
 find src/test/ -name '*.orig' -delete