diff --git a/src/Makefile b/src/Makefile
index bd6c187..57f9aad 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -396,7 +396,9 @@
 
 # MZSCHEME
 # Uncomment this when you want to include the MzScheme interface.
-# You may have to build racket from source to make this work.
+# You may have to build racket from source to make this work.  Version 7.9 has
+# been reported to work, version 8.0 probably doesn't work, version 8.5 has
+# been reported to work.
 # NOTE: does not work well together with valgrind.
 #CONF_OPT_MZSCHEME = --enable-mzschemeinterp
 # PLT/mrscheme/drscheme Home dir; the PLTHOME environment variable also works
diff --git a/src/eval.c b/src/eval.c
index c57f6a4..84a7b26 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1366,7 +1366,6 @@
 	    if (rettv != NULL && lp->ll_dict->dv_scope != 0)
 	    {
 		int prevval;
-		int wrong;
 
 		if (len != -1)
 		{
@@ -1375,7 +1374,7 @@
 		}
 		else
 		    prevval = 0; // avoid compiler warning
-		wrong = (lp->ll_dict->dv_scope == VAR_DEF_SCOPE
+		int wrong = (lp->ll_dict->dv_scope == VAR_DEF_SCOPE
 			       && (rettv->v_type == VAR_FUNC
 					    || rettv->v_type == VAR_PARTIAL)
 			       && var_wrong_func_name(key, lp->ll_di == NULL))
diff --git a/src/evalwindow.c b/src/evalwindow.c
index bc59251..3578669 100644
--- a/src/evalwindow.c
+++ b/src/evalwindow.c
@@ -89,6 +89,7 @@
 
 /*
  * Return the window and tab pointer of window "id".
+ * Returns NULL when not found.
  */
     win_T *
 win_id2wp_tp(int id, tabpage_T **tpp)
diff --git a/src/getchar.c b/src/getchar.c
index 57e184b..9ead903 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -968,18 +968,18 @@
  * Insert a string in position 'offset' in the typeahead buffer (for "@r"
  * and ":normal" command, vgetorpeek() and check_termcode()).
  *
- * If noremap is REMAP_YES, new string can be mapped again.
- * If noremap is REMAP_NONE, new string cannot be mapped again.
- * If noremap is REMAP_SKIP, first char of new string cannot be mapped again,
+ * If "noremap" is REMAP_YES, new string can be mapped again.
+ * If "noremap" is REMAP_NONE, new string cannot be mapped again.
+ * If "noremap" is REMAP_SKIP, first char of new string cannot be mapped again,
  * but abbreviations are allowed.
- * If noremap is REMAP_SCRIPT, new string cannot be mapped again, except for
+ * If "noremap" is REMAP_SCRIPT, new string cannot be mapped again, except for
  *			script-local mappings.
- * If noremap is > 0, that many characters of the new string cannot be mapped.
+ * If "noremap" is > 0, that many characters of the new string cannot be mapped.
  *
- * If nottyped is TRUE, the string does not return KeyTyped (don't use when
- * offset is non-zero!).
+ * If "nottyped" is TRUE, the string does not return KeyTyped (don't use when
+ * "offset" is non-zero!).
  *
- * If silent is TRUE, cmd_silent is set when the characters are obtained.
+ * If "silent" is TRUE, cmd_silent is set when the characters are obtained.
  *
  * return FAIL for failure, OK otherwise
  */
@@ -1601,8 +1601,8 @@
 }
 
 /*
- * updatescript() is called when a character can be written into the script file
- * or when we have waited some time for a character (c == 0)
+ * updatescript() is called when a character can be written into the script
+ * file or when we have waited some time for a character (c == 0)
  *
  * All the changed memfiles are synced if c == 0 or when the number of typed
  * characters reaches 'updatecount' and 'updatecount' is non-zero.
diff --git a/src/match.c b/src/match.c
index ceb317c..6ac6513 100644
--- a/src/match.c
+++ b/src/match.c
@@ -435,7 +435,7 @@
     colnr_T	matchcol;
     long	nmatched;
     int		called_emsg_before = called_emsg;
-    int         timed_out = FALSE;
+    int		timed_out = FALSE;
 
     // for :{range}s/pat only highlight inside the range
     if ((lnum < search_first_line || lnum > search_last_line) && cur == NULL)
diff --git a/src/message.c b/src/message.c
index d90666f..a60d330 100644
--- a/src/message.c
+++ b/src/message.c
@@ -1311,9 +1311,8 @@
 					|| c == K_X2MOUSE))
 				);
 	ui_breakcheck();
-	/*
-	 * Avoid that the mouse-up event causes visual mode to start.
-	 */
+
+	// Avoid that the mouse-up event causes Visual mode to start.
 	if (c == K_LEFTMOUSE || c == K_MIDDLEMOUSE || c == K_RIGHTMOUSE
 					  || c == K_X1MOUSE || c == K_X2MOUSE)
 	    (void)jump_to_mouse(MOUSE_SETPOS, NULL, 0);
diff --git a/src/move.c b/src/move.c
index aac2c24..66e8c18 100644
--- a/src/move.c
+++ b/src/move.c
@@ -2852,7 +2852,8 @@
 static void get_scroll_overlap(lineoff_T *lp, int dir);
 
 /*
- * Move screen "count" pages up or down and update screen.
+ * Move screen "count" pages up ("dir" is BACKWARD) or down ("dir" is FORWARD)
+ * and update the screen.
  *
  * Return FAIL for failure, OK otherwise.
  */
diff --git a/src/os_unix.c b/src/os_unix.c
index 814f3ad..db57902 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -2352,6 +2352,7 @@
 
 /*
  * Return TRUE if "name" looks like some xterm name.
+ * This matches "xterm.*", thus "xterm-256color", "xterm-kitty", etc.
  * Seiichi Sato mentioned that "mlterm" works like xterm.
  */
     int
@@ -2409,6 +2410,9 @@
     return 0;
 }
 
+/*
+ * Return TRUE if "name" is an iris-ansi terminal name.
+ */
     int
 vim_is_iris(char_u *name)
 {
@@ -2418,14 +2422,18 @@
 	    || STRCMP(name, "builtin_iris-ansi") == 0);
 }
 
+/*
+ * Return TRUE if "name" is a vt300-like terminal name.
+ */
     int
 vim_is_vt300(char_u *name)
 {
     if (name == NULL)
-	return FALSE;	       // actually all ANSI comp. terminals should be here
-    // catch VT100 - VT5xx
+	return FALSE;
+    // Actually all ANSI compatible terminals should be here.
+    // Catch at least VT1xx - VT5xx
     return ((STRNICMP(name, "vt", 2) == 0
-		&& vim_strchr((char_u *)"12345", name[2]) != NULL)
+			     && vim_strchr((char_u *)"12345", name[2]) != NULL)
 	    || STRCMP(name, "builtin_vt320") == 0);
 }
 
@@ -5011,8 +5019,7 @@
 					|| (!curbuf->b_p_bin
 					    && curbuf->b_p_fixeol)
 					|| (lnum != curbuf->b_no_eol_lnum
-					    && (lnum !=
-						    curbuf->b_ml.ml_line_count
+					    && (lnum != curbuf->b_ml.ml_line_count
 						    || curbuf->b_p_eol)))
 				    vim_ignored = write(toshell_fd, "\n",
 								   (size_t)1);
@@ -8309,8 +8316,8 @@
 start_timeout(long msec)
 {
     struct itimerspec interval = {
-	    {0, 0},                                   // Do not repeat.
-	    {msec / 1000, (msec % 1000) * 1000000}};  // Timeout interval
+	    {0, 0},					// Do not repeat.
+	    {msec / 1000, (msec % 1000) * 1000000}};	// Timeout interval
     int ret;
 
     // This is really the caller's responsibility, but let's make sure the
@@ -8323,8 +8330,8 @@
 
 	action.sigev_notify = SIGEV_THREAD;
 	action.sigev_notify_function = set_flag;
-        ret = timer_create(CLOCK_MONOTONIC, &action, &timer_id);
-        if (ret < 0)
+	ret = timer_create(CLOCK_MONOTONIC, &action, &timer_id);
+	if (ret < 0)
 	{
 	    semsg(_(e_could_not_set_timeout_str), strerror(errno));
 	    return &timeout_flag;
@@ -8362,10 +8369,10 @@
  * Implement timeout with setitimer()
  */
 static struct sigaction		prev_sigaction;
-static volatile sig_atomic_t	timeout_flag         = FALSE;
-static int			timer_active         = FALSE;
+static volatile sig_atomic_t	timeout_flag	     = FALSE;
+static int			timer_active	     = FALSE;
 static int			timer_handler_active = FALSE;
-static volatile sig_atomic_t	alarm_pending        = FALSE;
+static volatile sig_atomic_t	alarm_pending	     = FALSE;
 
 /*
  * Handle SIGALRM for a timeout.
@@ -8424,8 +8431,8 @@
 start_timeout(long msec)
 {
     struct itimerval	interval = {
-	    {0, 0},                                // Do not repeat.
-	    {msec / 1000, (msec % 1000) * 1000}};  // Timeout interval
+	    {0, 0},				    // Do not repeat.
+	    {msec / 1000, (msec % 1000) * 1000}};   // Timeout interval
     struct sigaction	handle_alarm;
     int			ret;
     sigset_t		sigs;
diff --git a/src/regexp_nfa.c b/src/regexp_nfa.c
index fc1a993..b829a3a 100644
--- a/src/regexp_nfa.c
+++ b/src/regexp_nfa.c
@@ -6782,8 +6782,7 @@
 			if (REG_MULTI && (lnum <= 0
 				   || lnum > wp->w_buffer->b_ml.ml_line_count))
 			    lnum = 1;
-			vcol = (long_u)win_linetabsize(wp, lnum,
-								rex.line, col);
+			vcol = (long_u)win_linetabsize(wp, lnum, rex.line, col);
 			result = nfa_re_num_cmp(t->state->val, op, vcol + 1);
 		    }
 		    if (result)
diff --git a/src/testdir/test_fileformat.vim b/src/testdir/test_fileformat.vim
index e7d1986..7d919c2 100644
--- a/src/testdir/test_fileformat.vim
+++ b/src/testdir/test_fileformat.vim
@@ -76,7 +76,12 @@
   call s:concat_files('XXMac', 'XXEol', 'XXMacEol')
   call s:concat_files('XXUxDs', 'XXMac', 'XXUxDsMc')
 
-  new
+  " The :bwipe commands below cause us to get back to the current buffer.
+  " Avoid stray errors for various 'fileformat' values which may cause a
+  " modeline to be misinterpreted by wiping the buffer and editing a new one.
+  only!
+  bwipe!
+  enew
 
   " Test 1: try reading and writing with 'fileformats' empty
   set fileformats=
diff --git a/src/testdir/test_function_lists.vim b/src/testdir/test_function_lists.vim
index 027a7a5..dd69b83 100644
--- a/src/testdir/test_function_lists.vim
+++ b/src/testdir/test_function_lists.vim
@@ -1,11 +1,11 @@
-" Test to verify that the three function lists,
+" Test to verify that the three function lists:
 "
-"   global_functions[] in src/evalfunc.c
-"   *functions* in runtime/doc/builtin.txt
-"   *function-list* in runtime/doc/usr_41.txt
+"  - global_functions[] in src/evalfunc.c
+"  - *functions* in runtime/doc/builtin.txt
+"  - *function-list* in runtime/doc/usr_41.txt
 "
-" contain the same functions and that the global_functions and ":help
-" functions" lists are in ASCII order.
+" contain the same functions and that the global_functions and
+" ":help functions" lists are in ASCII order.
 
 func Test_function_lists()
 
diff --git a/src/version.c b/src/version.c
index e0ba0ab..fbb6841 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    904,
+/**/
     903,
 /**/
     902,
diff --git a/src/winclip.c b/src/winclip.c
index 560759e..73fe92a 100644
--- a/src/winclip.c
+++ b/src/winclip.c
@@ -728,7 +728,8 @@
 /*
  * Convert from the active codepage to 'encoding'.
  * Input is "str[str_size]".
- * The result is in allocated memory: "out[outlen]".  With terminating NUL.
+ * The result is in allocated memory: "out[outlen]".  "outlen" includes the
+ * terminating NUL.
  */
     void
 acp_to_enc(