diff --git a/driver/iverilog.man.in b/driver/iverilog.man.in
index 3861690d2..56ba6d201 100644
--- a/driver/iverilog.man.in
+++ b/driver/iverilog.man.in
@@ -1,4 +1,4 @@
-.TH iverilog 1 "Oct 14th, 2017" "" "Version %M.%n%E"
+.TH iverilog 1 "Nov 8th, 2017" "" "Version %M.%n%E"
 .SH NAME
 iverilog - Icarus Verilog compiler
 
@@ -316,8 +316,9 @@ after a \fB\-Wall\fP argument to suppress isolated warning types.
 
 .TP 8
 .B all
-This enables the anachronisms, implicit, macro-redefinition, portbind,
-select\-range, timescale, and sensitivity\-entire\-array warning categories.
+This enables the anachronisms, implicit, macro-replacement, portbind,
+select\-range, timescale, and sensitivity\-entire\-array warning
+categories.
 
 .TP 8
 .B anachronisms
@@ -331,8 +332,11 @@ example, if a scalar wire X is used but not declared in the Verilog
 source, this will print a warning at its first use.
 
 .TP 8
-.B macro-redefinition
+.B macro-redefinition\fI | \fPmacro-replacement
 This enables preprocessor warnings when a macro is being redefined.
+The first variant prints a warning any time a macro is redefined.
+The second variant only prints a warning if the macro text changes.
+Use \fBno-macro-redefinition\fP to turn off all warnings of this type.
 
 .TP 8
 .B portbind
diff --git a/driver/main.c b/driver/main.c
index d12c40fe1..b723d7ff3 100644
--- a/driver/main.c
+++ b/driver/main.c
@@ -350,7 +350,8 @@ static void build_preprocess_command(int e_flag)
 	       ivlpp_dir, sep,
                verbose_flag ? " -v" : "",
 	       e_flag ? "" : " -L",
-               strchr(warning_flags, 'r') ? " -Wredef " : "",
+               strchr(warning_flags, 'r') ? " -Wredef-all " :
+               strchr(warning_flags, 'R') ? " -Wredef-chg " : "",
                defines_path, source_path,
 	       compiled_defines_path,
 	       e_flag ? "" : " | ");
@@ -520,14 +521,11 @@ static void process_warning_switch(const char*name)
 	    process_warning_switch("anachronisms");
 	    process_warning_switch("implicit");
 	    process_warning_switch("implicit-dimensions");
+	    process_warning_switch("macro-replacement");
 	    process_warning_switch("portbind");
 	    process_warning_switch("select-range");
 	    process_warning_switch("timescale");
 	    process_warning_switch("sensitivity-entire-array");
-	    process_warning_switch("macro-redefinition");
-      } else if (strcmp(name,"macro-redefinition") == 0) {
-          if (! strchr(warning_flags, 'r'))
- 		  strcat(warning_flags, "r");
       } else if (strcmp(name,"anachronisms") == 0) {
 	    if (! strchr(warning_flags, 'n'))
 		  strcat(warning_flags, "n");
@@ -540,6 +538,12 @@ static void process_warning_switch(const char*name)
       } else if (strcmp(name,"implicit-dimensions") == 0) {
 	    if (! strchr(warning_flags, 'd'))
 		  strcat(warning_flags, "d");
+      } else if (strcmp(name,"macro-redefinition") == 0) {
+	  if (! strchr(warning_flags, 'r'))
+		  strcat(warning_flags, "r");
+      } else if (strcmp(name,"macro-replacement") == 0) {
+	  if (! strchr(warning_flags, 'R'))
+		  strcat(warning_flags, "R");
       } else if (strcmp(name,"portbind") == 0) {
 	    if (! strchr(warning_flags, 'p'))
 		  strcat(warning_flags, "p");
@@ -566,12 +570,6 @@ static void process_warning_switch(const char*name)
 		  cp[0] = cp[1];
 		  cp += 1;
 	    }
-      } else if (strcmp(name,"no-macro-redefinition") == 0) {
-        char*cp = strchr(warning_flags, 'r');
-  	    if (cp) while (*cp) {
-  		  cp[0] = cp[1];
-  		  cp += 1;
-  	    }
       } else if (strcmp(name,"no-floating-nets") == 0) {
 	    char*cp = strchr(warning_flags, 'f');
 	    if (cp) while (*cp) {
@@ -590,6 +588,17 @@ static void process_warning_switch(const char*name)
 		  cp[0] = cp[1];
 		  cp += 1;
 	    }
+      } else if (strcmp(name,"no-macro-redefinition") == 0) {
+	    char*cp = strchr(warning_flags, 'r');
+	    if (cp) while (*cp) {
+		  cp[0] = cp[1];
+		  cp += 1;
+	    }
+	    cp = strchr(warning_flags, 'R');
+	    if (cp) while (*cp) {
+		  cp[0] = cp[1];
+		  cp += 1;
+	    }
       } else if (strcmp(name,"no-portbind") == 0) {
 	    char*cp = strchr(warning_flags, 'p');
 	    if (cp) while (*cp) {
@@ -1322,7 +1331,8 @@ int main(int argc, char **argv)
 	   files. */
       fprintf(iconfig_file, "ivlpp:%s%civlpp %s -L -F\"%s\" -P\"%s\"\n",
 	      ivlpp_dir, sep,
-              strchr(warning_flags, 'r') ? "-Wredef" : "",
+              strchr(warning_flags, 'r') ? "-Wredef-all" :
+              strchr(warning_flags, 'R') ? "-Wredef-chg" : "",
               defines_path, compiled_defines_path
       );
 
diff --git a/ivlpp/globals.h b/ivlpp/globals.h
index 1c4cee43d..a1f77e95e 100644
--- a/ivlpp/globals.h
+++ b/ivlpp/globals.h
@@ -1,7 +1,7 @@
 #ifndef IVL_globals_H
 #define IVL_globals_H
 /*
- * Copyright (c) 1999-2014 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1999-2017 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -54,6 +54,7 @@ extern char dep_mode;
 extern int verbose_flag;
 
 extern int warn_redef;
+extern int warn_redef_all;
 
 /* This is the entry to the lexer. */
 extern int yylex(void);
diff --git a/ivlpp/lexor.lex b/ivlpp/lexor.lex
index a74a8c357..5ab3e55de 100644
--- a/ivlpp/lexor.lex
+++ b/ivlpp/lexor.lex
@@ -1,7 +1,7 @@
 %option prefix="yy"
 %{
 /*
- * Copyright (c) 1999-2016 Stephen Williams (steve@icarus.com)
+ * Copyright (c) 1999-2017 Stephen Williams (steve@icarus.com)
  *
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -866,7 +866,7 @@ void define_macro(const char* name, const char* value, int keyword, int argc)
      */
     if (warn_redef) {
 	prev = def_lookup(name);
-	if (prev) {
+	if (prev && (warn_redef_all || (strcmp(prev->value, value) != 0))) {
 	    emit_pathline(istack);
 	    fprintf(stderr, "warning: redefinition of macro %s from value '%s' to '%s'\n",
 	    name, prev->value, value);
diff --git a/ivlpp/main.c b/ivlpp/main.c
index b4909b647..19ef09bde 100644
--- a/ivlpp/main.c
+++ b/ivlpp/main.c
@@ -1,5 +1,5 @@
 const char COPYRIGHT[] =
-          "Copyright (c) 1999-2015 Stephen Williams (steve@icarus.com)";
+          "Copyright (c) 1999-2017 Stephen Williams (steve@icarus.com)";
 /*
  *    This source code is free software; you can redistribute it
  *    and/or modify it in source code form under the terms of the GNU
@@ -100,6 +100,7 @@ FILE *depend_file = NULL;
 
 /* Should we warn about macro redefinitions? */
 int warn_redef = 0;
+int warn_redef_all = 0;
 
 static int flist_read_flags(const char*path)
 {
@@ -339,11 +340,14 @@ int main(int argc, char*argv[])
 		break;
 	  }
 
-	  case 'W': {
-		  if (strcmp(optarg, "redef")==0)
-		  	warn_redef = 1;
-		  break;
-	  }
+	  case 'W':
+	    if (strcmp(optarg, "redef-all") == 0) {
+		  warn_redef_all = 1;
+		  warn_redef = 1;
+	    } else if (strcmp(optarg, "redef-chg") == 0) {
+		  warn_redef = 1;
+	    }
+	    break;
 
 	  case 'v':
 	    fprintf(stderr, "Icarus Verilog Preprocessor version "
@@ -376,7 +380,9 @@ int main(int argc, char*argv[])
 		    "    -P<fil> - Read precompiled defines from <fil>\n"
 		    "    -v      - Verbose\n"
 		    "    -V      - Print version information and quit\n"
-			"    -W<cat> - Enable extra ivlpp warning category (e.g. redef)\n",
+		    "    -W<cat> - Enable extra ivlpp warning category:\n"
+		    "               o redef-all - all macro redefinitions\n"
+		    "               o redef-chg - macro definition changes\n",
 		    argv[0]);
 	    return flag_errors;
       }