diff --git a/h/cgg_cg.h b/h/cgg_cg.h
index 6cc04b007..b71685feb 100644
--- a/h/cgg_cg.h
+++ b/h/cgg_cg.h
@@ -4,6 +4,9 @@
  */
 /* $Id$ */
 
+#ifndef __CGG_CG_H_INCLUDED
+#define __CGG_CG_H_INCLUDED
+
 /* offsets of interesting fields in EM-pattern */
 
 #define PO_HASH         0
@@ -165,3 +168,5 @@ typedef struct {        /* one to one coercions */
 	if ((a=((*(b)++)&BMASK)) >= 128) {\
 		a = ((a-128)<<BSHIFT) | (*(b)++&BMASK); \
 	}
+
+#endif /* __CGG_CG_H_INCLUDED */
diff --git a/mach/proto/ncg/data.h b/mach/proto/ncg/data.h
index ddd232b98..dbba9914a 100644
--- a/mach/proto/ncg/data.h
+++ b/mach/proto/ncg/data.h
@@ -4,6 +4,8 @@
  */
 /* $Id$ */
 
+#include <cgg_cg.h> /* set_p, c3_p */
+
 typedef struct cost {
 	short ct_space;
 	short ct_time;
@@ -69,3 +71,20 @@ typedef struct {
 	int rl_n;       /* number in list */
 	int rl_list[NREGS];
 } rl_t,*rl_p;
+
+/* subr.c */
+int match(token_p, set_p, int);
+void instance(int, token_p);
+int eqtoken(token_p, token_p);
+int distance(int);
+unsigned costcalc(cost_t);
+int ssize(int);
+int tsize(token_p);
+void tref(token_p, int);
+int in_stack(int);
+#ifdef MAXSPLIT
+int split(token_p, int *, int, int);
+#endif
+unsigned docoerc(token_p, c3_p, int, int, int);
+unsigned stackupto(token_p, int, int);
+c3_p findcoerc(token_p, set_p);
diff --git a/mach/proto/ncg/main.c b/mach/proto/ncg/main.c
index 096b470f2..3336bc49b 100644
--- a/mach/proto/ncg/main.c
+++ b/mach/proto/ncg/main.c
@@ -4,6 +4,7 @@ static char rcsid[] = "$Id$";
 
 #include "param.h"
 #include "tables.h"
+#include "types.h" /* byte, codegen */
 #include "mach.h"
 
 /*
@@ -14,8 +15,7 @@ static char rcsid[] = "$Id$";
  */
 
 char *progname;
-extern char startupcode[];
-extern unsigned codegen();
+extern byte startupcode[]; /* codegen.c */
 int maxply=1;
 #ifndef NDEBUG
 int Debug=0;
@@ -25,6 +25,8 @@ char *strtdebug="";
 /* fillem.c */
 void in_init(char *);
 void in_start(void);
+/* subr.c */
+void itokcost(void);
 
 main(argc,argv) char **argv; {
 	register unsigned n;
diff --git a/mach/proto/ncg/move.c b/mach/proto/ncg/move.c
index d6bf6aa5e..7cce99b75 100644
--- a/mach/proto/ncg/move.c
+++ b/mach/proto/ncg/move.c
@@ -26,7 +26,6 @@ move(tp1,tp2,ply,toplevel,maxcost) token_p tp1,tp2; unsigned maxcost; {
 	register struct reginfo *rp;
 	register byte *tdpb;
 	int i;
-	unsigned codegen();
 
 	if (eqtoken(tp1,tp2))
 		return(0);
@@ -105,7 +104,6 @@ setcc(tp) token_p tp; {
 test(tp,ply,toplevel,maxcost) token_p tp; unsigned maxcost; {
 	register test_p mp;
 	unsigned t;
-	unsigned codegen();
 
 	if (cocoreg.t_token!=0) {
 		if (eqtoken(tp,&cocoreg))
diff --git a/mach/proto/ncg/subr.c b/mach/proto/ncg/subr.c
index 08861274d..81a021be1 100644
--- a/mach/proto/ncg/subr.c
+++ b/mach/proto/ncg/subr.c
@@ -24,10 +24,13 @@ static char rcsid[] = "$Id$";
  * Author: Hans van Staveren
  */
 
-unsigned codegen();
+static int from_stack(set_p);
+#ifdef TABLEDEBUG
+static void ruletrace(void);
+#endif
 
-match(tp,tep,optexp) register token_p tp; register set_p tep; {
-	register bitno;
+int match(token_p tp, set_p tep, int optexp) {
+	int bitno;
 	token_p ct;
 	result_t result;
 
@@ -52,11 +55,10 @@ match(tp,tep,optexp) register token_p tp; register set_p tep; {
 	return(result.e_v.e_con);
 }
 
-void
-instance(instno,token) register token_p token; {
-	register inst_p inp;
+void instance(int instno, token_p token) {
+	inst_p inp;
 	int i;
-	register token_p tp;
+	token_p tp;
 #if MAXMEMBERS != 0
 	struct reginfo *rp;
 #endif
@@ -70,7 +72,7 @@ instance(instno,token) register token_p token; {
 		return;
 	}
 	inp= &tokeninstances[instno];
-	switch(inp->in_which) {
+	switch (inp->in_which) {
 	default:
 		assert(FALSE);
 	case IN_COPY:
@@ -151,9 +153,8 @@ instance(instno,token) register token_p token; {
 	}
 }
 
-void
-cinstance(instno,token,tp,regno) register token_p token,tp; {
-	register inst_p inp;
+static void cinstance(int instno, token_p token, token_p tp, int regno) {
+	inst_p inp;
 	int i;
 #if MAXMEMBERS != 0
 	struct reginfo *rp;
@@ -163,7 +164,7 @@ cinstance(instno,token,tp,regno) register token_p token,tp; {
 
 	assert(instno!=0);
 	inp= &tokeninstances[instno];
-	switch(inp->in_which) {
+	switch (inp->in_which) {
 	default:
 		assert(FALSE);
 	case IN_COPY:
@@ -249,9 +250,9 @@ cinstance(instno,token,tp,regno) register token_p token,tp; {
 	}
 }
 
-eqtoken(tp1,tp2) token_p tp1,tp2; {
-	register i;
-	register tkdef_p tdp;
+int eqtoken(token_p tp1, token_p tp2) {
+	int i;
+	tkdef_p tdp;
 
 	if (tp1->t_token!=tp2->t_token)
 		return(0);
@@ -285,10 +286,10 @@ eqtoken(tp1,tp2) token_p tp1,tp2; {
 	return(1);
 }
 
-distance(cindex) {
-	register char *bp;
-	register i;
-	register token_p tp;
+int distance(int cindex) {
+	char *bp;
+	int i;
+	token_p tp;
 	int tokexp,tpl;
 	int expsize,toksize,exact;
 	int xsekt=0;
@@ -301,7 +302,7 @@ distance(cindex) {
 		getint(i,bp);
 	}
 #endif
-	switch( (*bp)&037 ) {
+	switch ( (*bp)&037 ) {
 	default:
 		return(stackheight==0 ? 0 : 100);
 	case DO_MATCH:
@@ -362,31 +363,29 @@ distance(cindex) {
 	return(20-2*exact+fromstackneeded);
 }
 
-extern set_t unstackset;
+extern set_t unstackset; /* tables.c */
 
-int from_stack(s1)
-	register set_p s1;
-{
-	register set_p s2 = &unstackset;
-	register int i;
+static int from_stack(set_p s1) {
+	set_p s2 = &unstackset;
+	int i;
 	for (i = 0; i < SETSIZE; i++) {
 		if ((s1->set_val[i] & s2->set_val[i]) != 0) return 1;
 	}
 	return 0;
 }
 
-unsigned costcalc(cost) cost_t cost; {
-	extern unsigned cc1,cc2,cc3,cc4;
+unsigned costcalc(cost_t cost) {
+	extern unsigned cc1,cc2,cc3,cc4; /* tables.c */
 
 	return(cost.ct_space*cc1/cc2 + cost.ct_time*cc3/cc4);
 }
 
-ssize(tokexpno) {
+int ssize(int tokexpno) {
 
 	return(machsets[tokexpno].set_size);
 }
 
-tsize(tp) register token_p tp; {
+int tsize(token_p tp) {
 
 	if (tp->t_token==-1)
 		return(machregs[tp->t_att[0].ar].r_size);
@@ -394,12 +393,12 @@ tsize(tp) register token_p tp; {
 }
 
 #ifdef MAXSPLIT
-instsize(tinstno,tp) token_p tp; {
+static int instsize(int tinstno, token_p tp) {
 	inst_p inp;
 	struct reginfo *rp;
 
 	inp = &tokeninstances[tinstno];
-	switch(inp->in_which) {
+	switch (inp->in_which) {
 	default:
 		assert(FALSE);
 	case IN_COPY:
@@ -427,9 +426,9 @@ instsize(tinstno,tp) token_p tp; {
 }
 #endif /* MAXSPLIT */
 
-tref(tp,amount) register token_p tp; {
-	register i;
-	register byte *tdpb;
+void tref(token_p tp, int amount) {
+	int i;
+	byte *tdpb;
 
 	if (tp->t_token==-1)
 		chrefcount(tp->t_att[0].ar,amount,FALSE);
@@ -446,10 +445,10 @@ tref(tp,amount) register token_p tp; {
    restore it and check whether a certain register is present in the
    saved stack
 */
-token_t aside[MAXSAVE] ;
-int	aside_length = -1 ;
+static token_t	aside[MAXSAVE] ;
+static int	aside_length = -1 ;
 
-save_stack(tp) register token_p tp ; {
+static void save_stack(token_p tp) {
 	int i ;
 	token_p tmp = &fakestack[stackheight - 1];
 
@@ -467,10 +466,10 @@ save_stack(tp) register token_p tp ; {
 	stackheight -= aside_length;
 }
 
-in_stack(reg) {
-	register token_p tp ;
-	register i ;
-	register tkdef_p tdp ;
+int in_stack(int reg) {
+	token_p tp ;
+	int i ;
+	tkdef_p tdp ;
 
 	for ( i=0, tp=aside ; i<aside_length ; i++, tp++ )
 		if (tp->t_token==-1) {
@@ -493,8 +492,8 @@ gotone:
 	return 1 ;
 }
 
-rest_stack() {
-	register int i ;
+static void rest_stack(void) {
+	int i ;
 
 	assert(aside_length!= -1); 
 #ifndef NDEBUG
@@ -508,11 +507,11 @@ rest_stack() {
 }
 
 #ifdef MAXSPLIT
-split(tp,ip,ply,toplevel) token_p tp; register int *ip; {
-	register c2_p cp;
+int split(token_p tp, int *ip, int ply, int toplevel) {
+	c2_p cp;
 	token_t savestack[MAXSAVE];
 	int ok;
-	register i;
+	int i;
 	int diff;
 	token_p stp;
 	int tpl;
@@ -542,7 +541,7 @@ found:
 }
 #endif /* MAXSPLIT */
 
-unsigned docoerc(tp,cp,ply,toplevel,forced) token_p tp; register c3_p cp; {
+unsigned docoerc(token_p tp, c3_p cp, int ply, int toplevel, int forced) {
 	unsigned cost;
 	int tpl;        /* saved tokpatlen */
 
@@ -556,7 +555,7 @@ unsigned docoerc(tp,cp,ply,toplevel,forced) token_p tp; register c3_p cp; {
 	return(cost);
 }
 
-unsigned stackupto(limit,ply,toplevel) token_p limit; {
+unsigned stackupto(token_p limit, int ply, int toplevel) {
 	token_t savestack[MAXFSTACK];
 	token_p stp;
 	int i,diff;
@@ -620,7 +619,7 @@ unsigned stackupto(limit,ply,toplevel) token_p limit; {
 	return(totalcost);
 }
 
-c3_p findcoerc(tp,tep) token_p tp; set_p tep; {
+c3_p findcoerc(token_p tp, set_p tep) {
 	register c3_p cp;
 	token_t rtoken;
 	register i;
@@ -657,8 +656,8 @@ c3_p findcoerc(tp,tep) token_p tp; set_p tep; {
 	return(0);      /* nothing found */
 }
 
-itokcost() {
-	register tkdef_p tdp;
+void itokcost(void) {
+	tkdef_p tdp;
 
 	for(tdp=tokens+1;tdp->t_size!=0;tdp++)
 		tdp->t_cost.ct_space = costcalc(tdp->t_cost);
@@ -695,8 +694,8 @@ void fatal(const char *s, ...) {
 
 #ifdef TABLEDEBUG
 
-ruletrace() {
-	register i;
+static void ruletrace(void) {
+	int i;
 	extern int tablelines[MAXTDBUG];
 	extern int ntableline;
 	extern char *tablename;
diff --git a/mach/proto/ncg/types.h b/mach/proto/ncg/types.h
index 91625557d..1867853ca 100644
--- a/mach/proto/ncg/types.h
+++ b/mach/proto/ncg/types.h
@@ -29,6 +29,8 @@ typedef char * string;
 #define WRD_FMT "%ld"
 #endif /* WRD_FMT */
 
+/* codegen.c */
+unsigned codegen(byte *, int, int, unsigned, int);
 /* compute.c */
 string mystrcpy(string);
 string tostring(word);