diff --git a/unproto/error.c b/unproto/error.c
index 667d978cbb..2fbccacb4d 100644
--- a/unproto/error.c
+++ b/unproto/error.c
@@ -53,7 +53,7 @@
 
 #include <stdio.h>
 
-extern void exit();
+extern void exit(int status);
 
 /* Application-specific stuff */
 
diff --git a/unproto/error.h b/unproto/error.h
index dfb27e9067..cb52ae646b 100644
--- a/unproto/error.h
+++ b/unproto/error.h
@@ -1,6 +1,6 @@
 /* @(#) error.h 1.2 92/01/15 21:53:14 */
 
 extern int errcount;			/* error counter */
-extern void error();			/* default context */
-extern void error_where();		/* user-specified context */
-extern void fatal();			/* fatal error */
+extern void error(char *text);			/* default context */
+extern void error_where(char *path, int line, char *text);		/* user-specified context */
+extern void fatal(char *text);			/* fatal error */
diff --git a/unproto/strsave.c b/unproto/strsave.c
index 2ee00b4172..faa4e18686 100644
--- a/unproto/strsave.c
+++ b/unproto/strsave.c
@@ -28,7 +28,7 @@
 #include <string.h>
 
 extern int hash(register char *s, unsigned size);
-extern char *malloc();
+extern char *malloc(long size);
 
 /* Application-specific stuff */
 
diff --git a/unproto/symbol.c b/unproto/symbol.c
index 67a4bf0bc6..a4beab5e92 100644
--- a/unproto/symbol.c
+++ b/unproto/symbol.c
@@ -45,7 +45,7 @@
 #include <string.h>
 
 extern int hash(register char *s, unsigned size);
-extern char *malloc();
+extern char *malloc(long size);
 
 /* Application-specific stuff */
 
diff --git a/unproto/symbol.h b/unproto/symbol.h
index 0711c1f4dc..0e2b1d88f8 100644
--- a/unproto/symbol.h
+++ b/unproto/symbol.h
@@ -6,6 +6,6 @@
     struct symbol *next;
 };
 
-extern void sym_enter();		/* add symbol to table */
-extern struct symbol *sym_find();	/* locate symbol */
+extern void sym_enter(char *name, int type);		/* add symbol to table */
+extern struct symbol *sym_find(register char *name);	/* locate symbol */
 extern void sym_init();			/* prime the table */
diff --git a/unproto/tok_class.c b/unproto/tok_class.c
index 04207a07f3..9af67188ca 100644
--- a/unproto/tok_class.c
+++ b/unproto/tok_class.c
@@ -51,8 +51,8 @@
 #include <stdio.h>
 #include <string.h>
 
-extern long time();
-extern char* ctime();
+extern long time(long *tloc);
+extern char* ctime(long *clock);
 
 /* Application-specific stuff */
 
@@ -61,13 +61,13 @@
 #include "token.h"
 #include "symbol.h"
 
-static struct token *tok_list();
-static void tok_list_struct();
-static void tok_list_append();
-static void tok_strcat();
-static void tok_time();
-static void tok_date();
-static void tok_space_append();
+static struct token *tok_list(struct token *t);
+static void tok_list_struct(register struct token *list, register struct token *t);
+static void tok_list_append(struct token *h, struct token *t);
+static void tok_strcat(register struct token *t1);
+static void tok_time(struct token *t);
+static void tok_date(struct token *t);
+static void tok_space_append(register struct token *list, register struct token *t);
 
 #if defined(MAP_VOID_STAR) || defined(MAP_VOID)
 static void tok_void();			/* rewrite void keyword */
diff --git a/unproto/tok_io.c b/unproto/tok_io.c
index 288950b3ac..773ca5bf4d 100644
--- a/unproto/tok_io.c
+++ b/unproto/tok_io.c
@@ -89,7 +89,7 @@
 #include "vstring.h"
 #include "error.h"
 
-extern char *strsave();			/* XXX need include file */
+extern char *strsave(register char *str);			/* XXX need include file */
 
 /* Stuff to keep track of original source file name and position */
 
@@ -104,12 +104,12 @@
 
 /* Forward declarations */
 
-static int read_quoted();
-static void read_comment();
+static int read_quoted(register struct vstring *vs, int ch);
+static void read_comment(register struct vstring *vs);
 static int backslash_newline();
-static char *read_hex();
-static char *read_octal();
-static void fix_line_control();
+static char *read_hex(struct vstring *vs, register char *cp);
+static char *read_octal(register struct vstring *vs, register char *cp, register int c);
+static void fix_line_control(register char *path, register int line);
 
  /*
   * Character input with one level of pushback. The INPUT() macro recursively
diff --git a/unproto/tok_pool.c b/unproto/tok_pool.c
index e2ed107ce7..bbe3d184c5 100644
--- a/unproto/tok_pool.c
+++ b/unproto/tok_pool.c
@@ -37,7 +37,7 @@
 
 /* C library */
 
-extern char *malloc();
+extern char *malloc(long size);
 
 /* Application-specific stuff */
 
diff --git a/unproto/token.h b/unproto/token.h
index bb2f50a106..e3752a0eb3 100644
--- a/unproto/token.h
+++ b/unproto/token.h
@@ -27,11 +27,11 @@
 /* Input/output functions and macros */
 
 extern struct token *tok_get();		/* read next single token */
-extern void tok_show();			/* display (composite) token */
+extern void tok_show(register struct token *t);			/* display (composite) token */
 extern struct token *tok_class();	/* classify tokens */
-extern void tok_unget();		/* stuff token back into input */
+extern void tok_unget(register struct token *t);		/* stuff token back into input */
 extern void put_nl();			/* print newline character */
-extern void tok_show_ch();		/* emit single-character token */
+extern void tok_show_ch(register struct token *t);		/* emit single-character token */
 
 #define	tok_flush(t)	(tok_show(t), tok_free(t))
 
@@ -46,7 +46,7 @@
 /* Memory management */
 
 struct token *tok_alloc();		/* allocate token storage */
-extern void tok_free();			/* re-cycle storage */
+extern void tok_free(register struct token *t);			/* re-cycle storage */
 
 /* Context */
 
diff --git a/unproto/unproto.c b/unproto/unproto.c
index 18fc2aaecf..802b91dd3e 100644
--- a/unproto/unproto.c
+++ b/unproto/unproto.c
@@ -140,7 +140,7 @@
 #include <errno.h>
 #include <string.h>
 
-extern void exit();
+extern void exit(int status);
 extern int optind;
 extern char *optarg;
 extern int getopt();
@@ -159,16 +159,16 @@
 
 /* Forward declarations. */
 
-static struct token *dcl_flush();
-static void block_flush();
+static struct token *dcl_flush(register struct token *t);
+static void block_flush(register struct token *t);
 static void block_dcls();
-static struct token *show_func_ptr_type();
-static struct token *show_struct_type();
-static void show_arg_name();
-static void show_type();
-static void pair_flush();
-static void check_cast();
-static void show_empty_list();
+static struct token *show_func_ptr_type(struct token *t1, struct token *t2);
+static struct token *show_struct_type(register struct token *p);
+static void show_arg_name(register struct token *s);
+static void show_type(register struct token *s);
+static void pair_flush(register struct token *t, register int start, register int stop);
+static void check_cast(struct token *t);
+static void show_empty_list(register struct token *t);
 
 #define	check_cast_flush(t)	(check_cast(t), tok_free(t))
 
diff --git a/unproto/vstring.c b/unproto/vstring.c
index 220bd530fe..ef9bcffa3c 100644
--- a/unproto/vstring.c
+++ b/unproto/vstring.c
@@ -67,8 +67,8 @@
 
 /* C library */
 
-extern char *malloc();
-extern char *realloc();
+extern char *malloc(long size);
+extern char *realloc(char *p, long size);
 
 /* Application-specific stuff */
 
diff --git a/unproto/vstring.h b/unproto/vstring.h
index c2e1f88a77..16a17aa815 100644
--- a/unproto/vstring.h
+++ b/unproto/vstring.h
@@ -5,9 +5,9 @@
     char   *last;			/* last position */
 };
 
-extern struct vstring *vs_alloc();	/* initial allocation */
-extern char *vs_realloc();		/* string extension */
-extern char *vs_strcpy();		/* copy string */
+extern struct vstring *vs_alloc(int len);	/* initial allocation */
+extern char *vs_realloc(register struct vstring *vp, char *cp);		/* string extension */
+extern char *vs_strcpy(register struct vstring *vp, register char *dst, register char *src);		/* copy string */
 
 /* macro to add one character to auto-resized string */