diff --git a/runtime/doc/cmdline.txt b/runtime/doc/cmdline.txt
index 214571f..404e54d 100644
--- a/runtime/doc/cmdline.txt
+++ b/runtime/doc/cmdline.txt
@@ -1,4 +1,4 @@
-*cmdline.txt*   For Vim version 9.1.  Last change: 2024 Apr 27
+*cmdline.txt*   For Vim version 9.1.  Last change: 2024 Aug 15
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -379,7 +379,7 @@
 
 :keepp[atterns] {command}			*:keepp* *:keeppatterns*
 		Execute {command}, without adding anything to the search
-		history
+		history or modifying the last substitute pattern.
 
 ==============================================================================
 2. Command-line completion				*cmdline-completion*
diff --git a/runtime/doc/version9.txt b/runtime/doc/version9.txt
index 73e54a1..3729590 100644
--- a/runtime/doc/version9.txt
+++ b/runtime/doc/version9.txt
@@ -1,4 +1,4 @@
-*version9.txt*  For Vim version 9.1.  Last change: 2024 Jul 30
+*version9.txt*  For Vim version 9.1.  Last change: 2024 Aug 15
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -41592,6 +41592,7 @@
   mark deprecated attributes from LSP server) |complete-items|
 - the regex engines match correctly case-insensitive multi-byte characters
   (and apply proper case folding)
+- |:keeppatterns| preserves the last substitute pattern when used with |:s|
 
 							*added-9.2*
 Added ~
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 4793737..05778c8 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -3777,6 +3777,7 @@
     int		endcolumn = FALSE;	// cursor in last column when done
     pos_T	old_cursor = curwin->w_cursor;
     int		start_nsubs;
+    int		keeppatterns = cmdmod.cmod_flags & CMOD_KEEPPATTERNS;
 #ifdef FEAT_EVAL
     int		save_ma = 0;
     int		save_sandbox = 0;
@@ -3876,7 +3877,7 @@
 		    // out of memory
 		    return;
 	    }
-	    else
+	    else if (!keeppatterns)
 	    {
 		vim_free(old_sub);
 		old_sub = vim_strsave(sub);
@@ -3940,7 +3941,7 @@
 	    ex_may_print(eap);
 	}
 
-	if ((cmdmod.cmod_flags & CMOD_KEEPPATTERNS) == 0)
+	if (!keeppatterns)
 	    save_re_pat(RE_SUBST, pat, patlen, magic_isset());
 	// put pattern in history
 	add_to_history(HIST_SEARCH, pat, patlen, TRUE, NUL);
diff --git a/src/testdir/test_substitute.vim b/src/testdir/test_substitute.vim
index afdc104..b25cd60 100644
--- a/src/testdir/test_substitute.vim
+++ b/src/testdir/test_substitute.vim
@@ -806,7 +806,7 @@
   a
 foobar
 
-substitute foo asdf
+substitute foo asdf foo
 
 one two
 .
@@ -815,21 +815,26 @@
   /^substitute
   s/foo/bar/
   call assert_equal('foo', @/)
-  call assert_equal('substitute bar asdf', getline('.'))
+  call assert_equal('substitute bar asdf foo', getline('.'))
 
   /^substitute
   keeppatterns s/asdf/xyz/
   call assert_equal('^substitute', @/)
-  call assert_equal('substitute bar xyz', getline('.'))
+  call assert_equal('substitute bar xyz foo', getline('.'))
+
+  /^substitute
+  &
+  call assert_equal('^substitute', @/)
+  call assert_equal('substitute bar xyz bar', getline('.'))
 
   exe "normal /bar /e\<CR>"
   call assert_equal(15, col('.'))
   normal -
   keeppatterns /xyz
   call assert_equal('bar ', @/)
-  call assert_equal('substitute bar xyz', getline('.'))
+  call assert_equal('substitute bar xyz bar', getline('.'))
   exe "normal 0dn"
-  call assert_equal('xyz', getline('.'))
+  call assert_equal('xyz bar', getline('.'))
 
   close!
 endfunc
diff --git a/src/version.c b/src/version.c
index e4fb2ca..78ccd20 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    677,
+/**/
     676,
 /**/
     675,