diff --git a/usr.bin/checknr/checknr.c b/usr.bin/checknr/checknr.c
index 336eb6757f3..f8531cc7da1 100644
--- a/usr.bin/checknr/checknr.c
+++ b/usr.bin/checknr/checknr.c
@@ -49,12 +49,27 @@ static char sccsid[] = "@(#)checknr.c	8.1 (Berkeley) 6/6/93";
  * structured typesetting.
  */
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <ctype.h>
 
 #define MAXSTK	100	/* Stack size */
 #define MAXBR	100	/* Max number of bracket pairs known */
 #define MAXCMDS	500	/* Max number of commands known */
 
+void addcmd __P((char *));
+void addmac __P((char *));
+int binsrch __P((char *));
+void checkknown __P((char *));
+void chkcmd __P((char *, char *));
+void complain __P((int));
+int eq __P((char *, char *));
+void nomatch __P((char *));
+void pe __P((int));
+void process __P((FILE *));
+void prop __P((int));
+static void usage __P((void));
+
 /*
  * The stack on which we remember what we've seen so far.
  */
@@ -75,53 +90,53 @@ struct brstr {
 } br[MAXBR] = {
 	/* A few bare bones troff commands */
 #define SZ	0
-	"sz",	"sz",	/* also \s */
+	{"sz",	"sz"},	/* also \s */
 #define FT	1
-	"ft",	"ft",	/* also \f */
+	{"ft",	"ft"},	/* also \f */
 	/* the -mm package */
-	"AL",	"LE",
-	"AS",	"AE",
-	"BL",	"LE",
-	"BS",	"BE",
-	"DF",	"DE",
-	"DL",	"LE",
-	"DS",	"DE",
-	"FS",	"FE",
-	"ML",	"LE",
-	"NS",	"NE",
-	"RL",	"LE",
-	"VL",	"LE",
+	{"AL",	"LE"},
+	{"AS",	"AE"},
+	{"BL",	"LE"},
+	{"BS",	"BE"},
+	{"DF",	"DE"},
+	{"DL",	"LE"},
+	{"DS",	"DE"},
+	{"FS",	"FE"},
+	{"ML",	"LE"},
+	{"NS",	"NE"},
+	{"RL",	"LE"},
+	{"VL",	"LE"},
 	/* the -ms package */
-	"AB",	"AE",
-	"BD",	"DE",
-	"CD",	"DE",
-	"DS",	"DE",
-	"FS",	"FE",
-	"ID",	"DE",
-	"KF",	"KE",
-	"KS",	"KE",
-	"LD",	"DE",
-	"LG",	"NL",
-	"QS",	"QE",
-	"RS",	"RE",
-	"SM",	"NL",
-	"XA",	"XE",
-	"XS",	"XE",
+	{"AB",	"AE"},
+	{"BD",	"DE"},
+	{"CD",	"DE"},
+	{"DS",	"DE"},
+	{"FS",	"FE"},
+	{"ID",	"DE"},
+	{"KF",	"KE"},
+	{"KS",	"KE"},
+	{"LD",	"DE"},
+	{"LG",	"NL"},
+	{"QS",	"QE"},
+	{"RS",	"RE"},
+	{"SM",	"NL"},
+	{"XA",	"XE"},
+	{"XS",	"XE"},
 	/* The -me package */
-	"(b",	")b",
-	"(c",	")c",
-	"(d",	")d",
-	"(f",	")f",
-	"(l",	")l",
-	"(q",	")q",
-	"(x",	")x",
-	"(z",	")z",
+	{"(b",	")b"},
+	{"(c",	")c"},
+	{"(d",	")d"},
+	{"(f",	")f"},
+	{"(l",	")l"},
+	{"(q",	")q"},
+	{"(x",	")x"},
+	{"(z",	")z"},
 	/* Things needed by preprocessors */
-	"EQ",	"EN",
-	"TS",	"TE",
+	{"EQ",	"EN"},
+	{"TS",	"TE"},
 	/* Refer */
-	"[",	"]",
-	0,	0
+	{"[",	"]"},
+	{0,	0}
 };
 
 /*
@@ -171,8 +186,7 @@ int	sflag;		/* -s: ignore \s */
 int	ncmds;		/* size of knowncmds */
 int	slot;		/* slot in knowncmds found by binsrch */
 
-char	*malloc();
-
+int
 main(argc, argv)
 int argc;
 char **argv;
@@ -254,12 +268,15 @@ char **argv;
 	exit(0);
 }
 
+static void
 usage()
 {
-	printf("Usage: checknr -s -f -a.xx.yy.xx.yy... -c.xx.xx.xx...\n");
+	fprintf(stderr,
+	"usage: checknr [-a.xx.yy.xx.yy...] [-c.xx.xx.xx...] [-s] [-f] file\n");
 	exit(1);
 }
 
+void
 process(f)
 FILE *f;
 {
@@ -356,7 +373,9 @@ FILE *f;
 	}
 }
 
+void
 complain(i)
+int i;
 {
 	pe(stk[i].lno);
 	printf("Unmatched ");
@@ -364,7 +383,9 @@ complain(i)
 	printf("\n");
 }
 
+void
 prop(i)
+int i;
 {
 	if (stk[i].pl == 0)
 		printf(".%s", br[stk[i].opno].opbr);
@@ -381,11 +402,12 @@ prop(i)
 	}
 }
 
+void
 chkcmd(line, mac)
 char *line;
 char *mac;
 {
-	register int i, n;
+	register int i;
 
 	/*
 	 * Check to see if it matches top of stack.
@@ -418,6 +440,7 @@ char *mac;
 	}
 }
 
+void
 nomatch(mac)
 char *mac;
 {
@@ -463,6 +486,7 @@ char *mac;
 }
 
 /* eq: are two strings equal? */
+int
 eq(s1, s2)
 char *s1, *s2;
 {
@@ -470,6 +494,7 @@ char *s1, *s2;
 }
 
 /* print the first part of an error message, given the line number */
+void
 pe(lineno)
 int lineno;
 {
@@ -478,6 +503,7 @@ int lineno;
 	printf("%d: ", lineno);
 }
 
+void
 checkknown(mac)
 char *mac;
 {
@@ -496,6 +522,7 @@ char *mac;
 /*
  * We have a .de xx line in "line".  Add xx to the list of known commands.
  */
+void
 addcmd(line)
 char *line;
 {
@@ -527,6 +554,7 @@ char *line;
  * me someday?)  Anyway, I claim that .de is fairly rare in user
  * nroff programs, and the register loop below is pretty fast.
  */
+void
 addmac(mac)
 char *mac;
 {
@@ -559,6 +587,7 @@ printf("after: %s %s %s %s %s, %d cmds\n", knowncmds[slot-2], knowncmds[slot-1],
  * Do a binary search in knowncmds for mac.
  * If found, return the index.  If not, return -1.
  */
+int
 binsrch(mac)
 char *mac;
 {