diff --git a/runtime/doc/cmdline.txt b/runtime/doc/cmdline.txt
index f306067a9c..fa68d69371 100644
--- a/runtime/doc/cmdline.txt
+++ b/runtime/doc/cmdline.txt
@@ -348,7 +348,7 @@ terminals)
 
 :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/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 8c536d4838..5e87936be1 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -3085,7 +3085,7 @@ void sub_set_replacement(SubReplacementString sub)
 ///
 /// @returns true if :substitute can be replaced with a join command
 static bool sub_joining_lines(exarg_T *eap, char *pat, size_t patlen, const char *sub,
-                              const char *cmd, bool save)
+                              const char *cmd, bool save, bool keeppatterns)
   FUNC_ATTR_NONNULL_ARG(1, 4, 5)
 {
   // TODO(vim): find a generic solution to make line-joining operations more
@@ -3123,7 +3123,7 @@ static bool sub_joining_lines(exarg_T *eap, char *pat, size_t patlen, const char
     }
 
     if (save) {
-      if ((cmdmod.cmod_flags & CMOD_KEEPPATTERNS) == 0) {
+      if (!keeppatterns) {
         save_re_pat(RE_SUBST, pat, patlen, magic_isset());
       }
       // put pattern in history
@@ -3331,6 +3331,7 @@ static int do_sub(exarg_T *eap, const proftime_T timeout, const int cmdpreview_n
   linenr_T old_line_count = curbuf->b_ml.ml_line_count;
   char *sub_firstline;    // allocated copy of first sub line
   bool endcolumn = false;   // cursor in last column when done
+  const bool keeppatterns = cmdmod.cmod_flags & CMOD_KEEPPATTERNS;
   PreviewLines preview_lines = { KV_INITIAL_VALUE, 0 };
   static int pre_hl_id = 0;
   pos_T old_cursor = curwin->w_cursor;
@@ -3391,7 +3392,7 @@ static int do_sub(exarg_T *eap, const proftime_T timeout, const int cmdpreview_n
     cmd = skip_substitute(cmd, delimiter);
     sub = xstrdup(p);
 
-    if (!eap->skip && cmdpreview_ns <= 0) {
+    if (!eap->skip && !keeppatterns && cmdpreview_ns <= 0) {
       sub_set_replacement((SubReplacementString) {
         .sub = xstrdup(sub),
         .timestamp = os_time(),
@@ -3412,7 +3413,8 @@ static int do_sub(exarg_T *eap, const proftime_T timeout, const int cmdpreview_n
     endcolumn = (curwin->w_curswant == MAXCOL);
   }
 
-  if (sub != NULL && sub_joining_lines(eap, pat, patlen, sub, cmd, cmdpreview_ns <= 0)) {
+  if (sub != NULL && sub_joining_lines(eap, pat, patlen, sub, cmd, cmdpreview_ns <= 0,
+                                       keeppatterns)) {
     xfree(sub);
     return 0;
   }
diff --git a/test/old/testdir/test_substitute.vim b/test/old/testdir/test_substitute.vim
index f0a25b2804..90c46abe8b 100644
--- a/test/old/testdir/test_substitute.vim
+++ b/test/old/testdir/test_substitute.vim
@@ -806,7 +806,7 @@ func Test_replace_keeppatterns()
   a
 foobar
 
-substitute foo asdf
+substitute foo asdf foo
 
 one two
 .
@@ -815,21 +815,26 @@ one two
   /^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