diff --git a/sbin/ipfw/ipfw.8 b/sbin/ipfw/ipfw.8
index 7fb82725ede4..1d07fcdb5084 100644
--- a/sbin/ipfw/ipfw.8
+++ b/sbin/ipfw/ipfw.8
@@ -51,10 +51,9 @@
 .Op Fl q
 .Oo
 .Fl p Ar preproc
-.Oo Fl D
-.Ar macro Ns Op = Ns Ar value
+.Oo
+.Ar preproc-flags
 .Oc
-.Op Fl U Ar macro
 .Oc
 .Ar pathname
 .Sh DESCRIPTION
@@ -289,11 +288,8 @@ file systems are mounted (yet) by the time
 is being run (e.g. when they are mounted over NFS).
 Once
 .Fl p
-has been specified, optional
-.Fl D
-and
-.Fl U
-specifications can follow and will be passed on to the preprocessor.
+has been specified, any additional arguments as passed on to the preprocessor
+for interpretation.
 This allows for flexible configuration files (like conditionalizing
 them on the local hostname) and the use of macros to centralize
 frequently required arguments like IP addresses.
diff --git a/sbin/ipfw/ipfw.c b/sbin/ipfw/ipfw.c
index c4f00fd756d6..740aba8297eb 100644
--- a/sbin/ipfw/ipfw.c
+++ b/sbin/ipfw/ipfw.c
@@ -2529,28 +2529,8 @@ ipfw_readfile(int ac, char *av[])
 	pid_t	preproc = 0;
 	int	c;
 
-	while ((c = getopt(ac, av, "D:U:p:q")) != -1)
+	while ((c = getopt(ac, av, "p:q")) != -1) {
 		switch(c) {
-		case 'D':
-			if (!pflag)
-				errx(EX_USAGE, "-D requires -p");
-			if (i > MAX_ARGS - 2)
-				errx(EX_USAGE,
-				     "too many -D or -U options");
-			args[i++] = "-D";
-			args[i++] = optarg;
-			break;
-
-		case 'U':
-			if (!pflag)
-				errx(EX_USAGE, "-U requires -p");
-			if (i > MAX_ARGS - 2)
-				errx(EX_USAGE,
-				     "too many -D or -U options");
-			args[i++] = "-U";
-			args[i++] = optarg;
-			break;
-
 		case 'p':
 			pflag = 1;
 			cmd = optarg;
@@ -2567,6 +2547,19 @@ ipfw_readfile(int ac, char *av[])
 			     " summary ``ipfw''");
 		}
 
+		if (pflag)
+			break;
+	}
+
+	if (pflag) {
+		/* Pass all but the last argument to the preprocessor. */
+		while (optind < ac - 1) {
+			if (i >= MAX_ARGS)
+				errx(EX_USAGE, "too many preprocessor options");
+			args[i++] = av[optind++];
+		}
+	}
+
 	av += optind;
 	ac -= optind;
 	if (ac != 1)
diff --git a/sbin/ipfw/ipfw2.c b/sbin/ipfw/ipfw2.c
index e9ea0e10c954..c038dd373afd 100644
--- a/sbin/ipfw/ipfw2.c
+++ b/sbin/ipfw/ipfw2.c
@@ -3429,28 +3429,8 @@ ipfw_readfile(int ac, char *av[])
 	pid_t	preproc = 0;
 	int	c;
 
-	while ((c = getopt(ac, av, "D:U:p:q")) != -1)
+	while ((c = getopt(ac, av, "p:q")) != -1) {
 		switch(c) {
-		case 'D':
-			if (!pflag)
-				errx(EX_USAGE, "-D requires -p");
-			if (i > MAX_ARGS - 2)
-				errx(EX_USAGE,
-				     "too many -D or -U options");
-			args[i++] = "-D";
-			args[i++] = optarg;
-			break;
-
-		case 'U':
-			if (!pflag)
-				errx(EX_USAGE, "-U requires -p");
-			if (i > MAX_ARGS - 2)
-				errx(EX_USAGE,
-				     "too many -D or -U options");
-			args[i++] = "-U";
-			args[i++] = optarg;
-			break;
-
 		case 'p':
 			pflag = 1;
 			cmd = optarg;
@@ -3467,6 +3447,19 @@ ipfw_readfile(int ac, char *av[])
 			     " summary ``ipfw''");
 		}
 
+		if (pflag)
+			break;
+	}
+
+	if (pflag) {
+		/* Pass all but the last argument to the preprocessor. */
+		while (optind < ac - 1) {
+			if (i >= MAX_ARGS)
+				errx(EX_USAGE, "too many preprocessor options");
+			args[i++] = av[optind++];
+		}
+	}
+
 	av += optind;
 	ac -= optind;
 	if (ac != 1)