diff --git a/sys/unix/hints/macosx b/sys/unix/hints/macosx
index 10fac071d..594c6f8d2 100644
--- a/sys/unix/hints/macosx
+++ b/sys/unix/hints/macosx
@@ -45,7 +45,7 @@ GAMEGRP  = $(GAMEUID)
 
 
 #CC=gcc -W -Wimplicit -Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -DGCC_WARN
-CC=gcc -Wall -Wextra -Wno-missing-field-initializers -Wimplicit -Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -DGCC_WARN
+CC=gcc -Wall -Wextra -Wno-missing-field-initializers -Wimplicit -Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wwrite-strings -DGCC_WARN
 
 #
 # You shouldn't need to change anything below here.
@@ -131,10 +131,10 @@ ifdef WANT_WIN_X11
 endif
 endif
 
-CC=gcc -W -Wimplicit -Wreturn-type -Wunused -Wformat -Wswitch -Wshadow -Wcast-qual -Wwrite-strings -DGCC_WARN
 
 # ~/Library/Preferences/NetHack Defaults
 # OPTIONS=name:player,number_pad,menustyle:partial,!time,showexp
 # OPTIONS=hilite_pet,toptenwin,msghistory:200,windowtype:Qt
 #
-# Install.Qt mentions a patch for macos - it's not there.
+# Install.Qt mentions a patch for macos - it's not there (it seems to be in the Qt binary
+# package under the docs directory).
diff --git a/util/lev_comp.l b/util/lev_comp.l
index 4431a3fc9..9f6734f23 100644
--- a/util/lev_comp.l
+++ b/util/lev_comp.l
@@ -70,7 +70,7 @@ void FDECL(init_yyout, (FILE *));
  */
 extern YYSTYPE yylval;
 
-int line_number = 1, colon_line_number = 1;
+int nh_line_number = 1, colon_line_number = 1;
 static char map[4096];
 static int map_cnt = 0;
 
@@ -92,14 +92,14 @@ static int map_cnt = 0;
 		  int len = yyleng;
 		  /* convert \r\n to \n */
 		  if (len >= 2 && yytext[len - 2] == '\r') len -= 1;
-		  line_number++;
+		  nh_line_number++;
 		  (void) strncpy(map + map_cnt, yytext, len);
 		  map_cnt += len;
 		  map[map_cnt - 1] = '\n';
 		  map[map_cnt] = '\0';
 		}
-^#.*\n		{ line_number++; }
-:		{ colon_line_number = line_number; return ':'; }
+^#.*\n		{ nh_line_number++; }
+:		{ colon_line_number = nh_line_number; return ':'; }
 MESSAGE		return MESSAGE_ID;
 MAZE		return MAZE_ID;
 NOMAP		return NOMAP_ID;
@@ -107,7 +107,7 @@ LEVEL		return LEVEL_ID;
 INIT_MAP	return LEV_INIT_ID;
 FLAGS		return FLAGS_ID;
 GEOMETRY	return GEOMETRY_ID;
-^MAP\r?\n		{ BEGIN(MAPC); line_number++; }
+^MAP\r?\n		{ BEGIN(MAPC); nh_line_number++; }
 OBJECT		return OBJECT_ID;
 CONTAINER	return COBJECT_ID;
 MONSTER		return MONSTER_ID;
@@ -206,7 +206,7 @@ shortsighted	{ yylval.i=SHORTSIGHTED; return FLAG_TYPE; }
 		  yylval.map = (char *) alloc(strlen(yytext+1)+1);
 		  Strcpy(yylval.map, yytext+1); /* Discard the first \" */
 		  return STRING; }
-\r?\n		{ line_number++; }
+\r?\n		{ nh_line_number++; }
 [ \t]+		;
 '\\.'		{ yylval.i = yytext[2]; return CHAR; }
 '.'		{ yylval.i = yytext[1]; return CHAR; }
diff --git a/util/lev_main.c b/util/lev_main.c
index f08c88538..63a4ff331 100644
--- a/util/lev_main.c
+++ b/util/lev_main.c
@@ -209,7 +209,7 @@ extern unsigned int nfountain, npool, nsink;
 
 extern unsigned int max_x_map, max_y_map;
 
-extern int line_number, colon_line_number;
+extern int nh_line_number, colon_line_number;
 
 int
 main(argc, argv)
@@ -282,7 +282,7 @@ char **argv;
 		    } else {
 			init_yyin(fin);
 			(void) yyparse();
-			line_number = 1;
+			nh_line_number = 1;
 			if (fatal_error > 0) {
 				errors_encountered = TRUE;
 				fatal_error = 0;
@@ -308,7 +308,7 @@ yyerror(s)
 const char *s;
 {
 	(void) fprintf(stderr, "%s: line %d : %s\n", fname,
-		(*s >= 'A' && *s <= 'Z') ? colon_line_number : line_number, s);
+		(*s >= 'A' && *s <= 'Z') ? colon_line_number : nh_line_number, s);
 	if (++fatal_error > MAX_ERRORS) {
 		(void) fprintf(stderr,"Too many errors, good bye!\n");
 		exit(EXIT_FAILURE);
diff --git a/util/makedefs.c b/util/makedefs.c
index c3acc3b14..2d2c0b2eb 100644
--- a/util/makedefs.c
+++ b/util/makedefs.c
@@ -348,9 +348,16 @@ char	*options;
 static FILE *inputfp;
 static FILE *outputfp;
 
-#define TODO_GREP 1;
+struct grep_var {
+	const char *name;
+	int is_defined;		/* 0 undef; 1 defined */
+};
+/* struct grep_var grep_vars[] and TODO_* constants in include file: */
+#include "mdgrep.h"
+
 static void NDECL(do_grep);
 static void NDECL(do_grep_showvars);
+static struct grep_var *FDECL(grepsearch, (char *));
 static int grep_trace = 0;
 
 static void
@@ -403,7 +410,7 @@ do_ext_makedefs(int argc, char **argv){
 				Fprintf(stderr, "Can't do grep and something else.\n");
 				exit(EXIT_FAILURE);
 			}
-			todo = 1;
+			todo = TODO_GREP;
 			CONTINUE;
 		}
 		IS_OPTION("grep-showvars"){
@@ -414,11 +421,29 @@ do_ext_makedefs(int argc, char **argv){
 			grep_trace = 1;
 			CONTINUE;
 		}
-#ifdef notyet
 		IS_OPTION("grep-define"){
+			CONSUME;
+			struct grep_var *p = grepsearch(argv[0]);
+			if(p){
+				p->is_defined = 1;
+			} else {
+				Fprintf(stderr, "Unknown symbol '%s'\n", argv[0]);
+				exit(EXIT_FAILURE);
+			}
+			CONTINUE;
 		}
 		IS_OPTION("grep-undef"){
+			CONSUME;
+			struct grep_var *p = grepsearch(argv[0]);
+			if(p){
+				p->is_defined = 0;
+			} else {
+				Fprintf(stderr, "Unknown symbol '%s'\n", argv[0]);
+				exit(EXIT_FAILURE);
+			}
+			CONTINUE;
 		}
+#ifdef notyet
 		IS_OPTION("help"){
 		}
 #endif
@@ -438,7 +463,7 @@ do_ext_makedefs(int argc, char **argv){
 		case 0:
 			Fprintf(stderr, "Nothing to do?\n");
 			exit(EXIT_FAILURE);
-		case 1:
+		case TODO_GREP:
 			do_grep(); break;
 	}
 }
@@ -473,7 +498,9 @@ do_ext_makedefs(int argc, char **argv){
 */ 
 #define GREP_MAGIC '^'
 #define GREP_STACK_SIZE 100
+#ifdef notyet
 static int grep_rewrite = 0;	/* need to (possibly) rewrite lines */
+#endif
 static int grep_writing = 1;	/* need to copy lines to output */
 static int grep_errors = 0;
 static int grep_sp = 0;
@@ -484,13 +511,6 @@ static int grep_sp = 0;
 static int grep_stack[GREP_STACK_SIZE] = {ST_LD(1,0)};
 static int grep_lineno = 0;
 
-struct grep_var {
-	const char *name;
-	int is_defined;		/* 0 undef; 1 defined */
-};
-/* struct grep_var grep_vars[] in include file: */
-#include "mdgrep.h"
-
 static void
 do_grep_showvars(){
 	int x;
@@ -627,6 +647,7 @@ do_grep_control(buf)
 	return NULL;
 }
 
+#ifdef notyet
 static void
 do_grep_rewrite(buf)
 	char *buf;
@@ -634,6 +655,7 @@ do_grep_rewrite(buf)
 		/* no language features use this yet */
 	return;
 }
+#endif
 
 static void
 do_grep(){
@@ -670,8 +692,10 @@ do_grep(){
 		} else {
 			buf1 = buf;
 		}
+#ifdef notyet
 		if(grep_rewrite)
 			do_grep_rewrite(buf1);
+#endif
 		if(grep_writing)
 			Fprintf(outputfp, "%s\n", buf1);
 	}
diff --git a/util/mdgrep.h b/util/mdgrep.h
index 70c08e448..5444d1d28 100644
--- a/util/mdgrep.h
+++ b/util/mdgrep.h
@@ -264,4 +264,7 @@ static struct grep_var grep_vars[]={
 #endif
 	{0,0}
 };
+
+/* Command ids */
+#define TODO_GREP 1
 /* End of file */
diff --git a/util/mdgrep.pl b/util/mdgrep.pl
index 472a3611b..fc1475439 100644
--- a/util/mdgrep.pl
+++ b/util/mdgrep.pl
@@ -3,6 +3,10 @@
 # Copyright (c) Kenneth Lorber, Kensington, Maryland, 2008
 # NetHack may be freely redistributed.  See license for details.
 
+# MAKEDEFS:
+@commands = qw/grep/;
+
+# GREP:
 # Operating Systems:
 @os = qw/WIN32 MSDOS VMS UNIX TOS AMIGA MAC WINNT __BEOS__ WIN_CE OS2
 	WIN_CE_SMARTPHONE WIN_CE_POCKETPC WIN_CE_PS2xx
@@ -67,6 +71,8 @@ sub gen_magic {
 	}
 }
 
+# NB: Do NOT make grep_vars const - it needs to be writable for some debugging
+# options.
 sub gen_file {
 	print OUT "static struct grep_var grep_vars[]={\n";
 	foreach(@_){
@@ -87,8 +93,18 @@ E_O_M
 	print OUT "\t{0,0}\n};\n";
 }
 
+sub gen_commands {
+	local($x) = 1;
+	print OUT "\n/* Command ids */\n";
+	foreach(@commands){
+		print OUT "#define TODO_\U$_\E $x\n";
+	}
+	print OUT "\n";
+}
+
 &start_file;
 &gen_magic(0, @const_false);
 &gen_magic(1, @const_true);
 &gen_file(sort(@os,@win,@feature,@misc,@const_false,@const_true));
+&gen_commands;
 &end_file;