diff --git a/src/cmd/5a/a.h b/src/cmd/5a/a.h
index 550b61dcf36..a2c87cf489d 100644
--- a/src/cmd/5a/a.h
+++ b/src/cmd/5a/a.h
@@ -28,8 +28,6 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
-#include <u.h>
-#include <libc.h>
 #include <bio.h>
 #include "../5l/5.out.h"
 
@@ -54,7 +52,9 @@ typedef	struct	Hist	Hist;
 #define	NSYMB		8192
 #define	BUFSIZ		8192
 #define	HISTSZ		20
+#ifndef	EOF
 #define	EOF		(-1)
+#endif
 #define	IGN		(-2)
 #define	GETC()		((--fi.c < 0)? filbuf(): *fi.p++ & 0xff)
 #define	NHASH		503
diff --git a/src/cmd/5a/a.y b/src/cmd/5a/a.y
index b39c916ab1e..9a0efd5e065 100644
--- a/src/cmd/5a/a.y
+++ b/src/cmd/5a/a.y
@@ -29,7 +29,9 @@
 // THE SOFTWARE.
 
 %{
+#include <u.h>
 #include <stdio.h>	/* if we don't, bison will, and a.h re-#defines getc */
+#include <libc.h>
 #include "a.h"
 %}
 %union
diff --git a/src/cmd/5a/lex.c b/src/cmd/5a/lex.c
index 3978f1a6c13..ad7ed05ddd9 100644
--- a/src/cmd/5a/lex.c
+++ b/src/cmd/5a/lex.c
@@ -29,9 +29,10 @@
 // THE SOFTWARE.
 
 #define	EXTERN
+#include <u.h>
+#include <libc.h>
 #include "a.h"
 #include "y.tab.h"
-#include <ctype.h>
 
 enum
 {
diff --git a/src/cmd/5c/peep.c b/src/cmd/5c/peep.c
index c15bf0fc4cd..3a905f0997b 100644
--- a/src/cmd/5c/peep.c
+++ b/src/cmd/5c/peep.c
@@ -1122,7 +1122,6 @@ copyu(Prog *p, Adr *v, Adr *s)
 				return 3;
 		return 0;
 	}
-	return 0;
 }
 
 int
diff --git a/src/cmd/5c/reg.c b/src/cmd/5c/reg.c
index 8c97944184a..847b2b55012 100644
--- a/src/cmd/5c/reg.c
+++ b/src/cmd/5c/reg.c
@@ -83,6 +83,7 @@ regopt(Prog *p)
 	// the disable is unconventionally here because the call is in common code shared by 5c/6c/8c
 	return;
 
+#ifdef	NOTDEF
 	firstr = R;
 	lastr = R;
 	nvar = 0;
@@ -490,6 +491,7 @@ brk:
 		r1->link = freer;
 		freer = firstr;
 	}
+#endif
 }
 
 void
diff --git a/src/cmd/5c/swt.c b/src/cmd/5c/swt.c
index 431f0481731..7cbaadba962 100644
--- a/src/cmd/5c/swt.c
+++ b/src/cmd/5c/swt.c
@@ -380,10 +380,10 @@ outcode(void)
 		Bprint(&outbuf, "\n");
 		Bprint(&outbuf, "$$  // exports\n\n");
 		Bprint(&outbuf, "$$  // local types\n\n");
-		Bprint(&outbuf, "$$  // dynimport\n", thestring);
+		Bprint(&outbuf, "$$  // dynimport\n");
 		for(i=0; i<ndynimp; i++)
 			Bprint(&outbuf, "dynimport %s %s %s\n", dynimp[i].local, dynimp[i].remote, dynimp[i].path);
-		Bprint(&outbuf, "\n$$  // dynexport\n", thestring);
+		Bprint(&outbuf, "\n$$  // dynexport\n");
 		for(i=0; i<ndynexp; i++)
 			Bprint(&outbuf, "dynexport %s %s\n", dynexp[i].local, dynexp[i].remote);
 		Bprint(&outbuf, "\n$$\n\n");
diff --git a/src/cmd/5l/asm.c b/src/cmd/5l/asm.c
index 28de6255a61..15b7d974e7d 100644
--- a/src/cmd/5l/asm.c
+++ b/src/cmd/5l/asm.c
@@ -102,12 +102,15 @@ int	nelfsym = 1;
 void
 adddynrel(Sym *s, Reloc *r)
 {
+	USED(s);
+	USED(r);
 	diag("adddynrel: unsupported binary format");
 }
 
 void
 adddynsym(Sym *s)
 {
+	USED(s);
 	diag("adddynsym: not implemented");
 }
 
@@ -120,6 +123,9 @@ elfsetupplt(void)
 int
 archreloc(Reloc *r, Sym *s, vlong *val)
 {
+	USED(r);
+	USED(s);
+	USED(val);
 	return -1;
 }
 
@@ -452,7 +458,7 @@ asmb(void)
 		startva = INITTEXT - fo;	/* va of byte 0 of file */
 		
 		/* This null SHdr must appear before all others */
-		sh = newElfShdr(elfstr[ElfStrEmpty]);
+		newElfShdr(elfstr[ElfStrEmpty]);
 
 		/* program header info */
 		pph = newElfPhdr();
@@ -635,11 +641,11 @@ asmb(void)
 	cflush();
 	if(debug['c']){
 		print("textsize=%d\n", textsize);
-		print("datsize=%d\n", segdata.filelen);
-		print("bsssize=%d\n", segdata.len - segdata.filelen);
+		print("datsize=%ulld\n", segdata.filelen);
+		print("bsssize=%ulld\n", segdata.len - segdata.filelen);
 		print("symsize=%d\n", symsize);
 		print("lcsize=%d\n", lcsize);
-		print("total=%d\n", textsize+segdata.len+symsize+lcsize);
+		print("total=%lld\n", textsize+segdata.len+symsize+lcsize);
 	}
 }
 
@@ -1436,6 +1442,7 @@ if(debug['G']) print("%ux: %s: arm %d\n", (uint32)(p->pc), p->from.sym->name, p-
 	out[5] = o6;
 	return;
 
+#ifdef	NOTDEF
 	v = p->pc;
 	switch(o->size) {
 	default:
@@ -1491,6 +1498,7 @@ if(debug['G']) print("%ux: %s: arm %d\n", (uint32)(p->pc), p->from.sym->name, p-
 		lputl(o6);
 		break;
 	}
+#endif
 }
 
 int32
diff --git a/src/cmd/5l/l.h b/src/cmd/5l/l.h
index 182f3e738b9..dbd6b3cae05 100644
--- a/src/cmd/5l/l.h
+++ b/src/cmd/5l/l.h
@@ -31,7 +31,7 @@
 #include	<u.h>
 #include	<libc.h>
 #include	<bio.h>
-#include	"../5l/5.out.h"
+#include	"5.out.h"
 
 enum
 {
@@ -337,9 +337,11 @@ EXTERN	Prog*	prog_modu;
 #pragma	varargck	type	"A"	int
 #pragma	varargck	type	"C"	int
 #pragma	varargck	type	"D"	Adr*
+#pragma	varargck	type	"I"	uchar*
 #pragma	varargck	type	"N"	Adr*
 #pragma	varargck	type	"P"	Prog*
 #pragma	varargck	type	"S"	char*
+#pragma	varargck	type	"i"	char*
 
 int	Aconv(Fmt*);
 int	Cconv(Fmt*);
diff --git a/src/cmd/5l/obj.c b/src/cmd/5l/obj.c
index dd3a7329a2c..15f4b89cac9 100644
--- a/src/cmd/5l/obj.c
+++ b/src/cmd/5l/obj.c
@@ -151,11 +151,12 @@ main(int argc, char *argv[])
 	if(HEADTYPE == -1) {
 		if(debug['U'])
 			HEADTYPE = Hnoheader;
-		if(debug['B'])
+		else if(debug['B'])
 			HEADTYPE = Hrisc;
-		if(debug['9'])
+		else if(debug['9'])
 			HEADTYPE = Hplan9x32;
-		HEADTYPE = Hlinux;
+		else
+			HEADTYPE = Hlinux;
 	}
 	switch(HEADTYPE) {
 	default:
@@ -347,7 +348,6 @@ zaddr(Biobuf *f, Adr *a, Sym *h[])
 
 	case D_REGREG:
 		a->offset = Bgetc(f);
-		c++;
 		break;
 
 	case D_CONST2:
@@ -363,7 +363,6 @@ zaddr(Biobuf *f, Adr *a, Sym *h[])
 	case D_SCONST:
 		a->sval = mal(NSNAME);
 		Bread(f, a->sval, NSNAME);
-		c += NSNAME;
 		break;
 
 	case D_FCONST:
@@ -462,7 +461,6 @@ loop:
 		s = lookup(x, r);
 		if(x != name)
 			free(x);
-		name = nil;
 
 		if(sig != 0){
 			if(s->sig != 0 && s->sig != sig)
diff --git a/src/cmd/5l/pass.c b/src/cmd/5l/pass.c
index 194a1ed5f3a..c430494597c 100644
--- a/src/cmd/5l/pass.c
+++ b/src/cmd/5l/pass.c
@@ -246,7 +246,6 @@ patch(void)
 
 	for(cursym = textp; cursym != nil; cursym = cursym->next) {
 		for(p = cursym->text; p != P; p = p->link) {
-			a = p->as;
 			if(p->cond != P) {
 				p->cond = brloop(p->cond);
 				if(p->cond != P)
diff --git a/src/cmd/5l/prof.c b/src/cmd/5l/prof.c
index 48ad2dc594c..225a5243531 100644
--- a/src/cmd/5l/prof.c
+++ b/src/cmd/5l/prof.c
@@ -36,7 +36,7 @@
 void
 doprof1(void)
 {
-#if 0	// TODO(rsc)
+#ifdef	NOTDEF	// TODO(rsc)
 	Sym *s;
 	int32 n;
 	Prog *p, *q;
diff --git a/src/cmd/5l/span.c b/src/cmd/5l/span.c
index eb79f6b5a2b..d3da0278bfe 100644
--- a/src/cmd/5l/span.c
+++ b/src/cmd/5l/span.c
@@ -97,8 +97,6 @@ span(void)
 
 	bflag = 0;
 	c = INITTEXT;
-	op = nil;
-	p = nil;
 	otxt = c;
 	for(cursym = textp; cursym != nil; cursym = cursym->next) {
 		p = cursym->text;
@@ -224,7 +222,6 @@ span(void)
 	
 		bp = cursym->p;
 		for(p = p->link; p != P; p = p->link) {
-			curp = p;
 			pc = p->pc;
 			curp = p;
 			o = oplook(p);
@@ -234,7 +231,7 @@ span(void)
 				*bp++ = v;
 				*bp++ = v>>8;
 				*bp++ = v>>16;
-				*bp++ = v>>24;
+				*bp = v>>24;
 			}
 		}
 	}
@@ -463,8 +460,6 @@ aclass(Adr *a)
 				print("%D\n", a);
 				return C_GOK;
 			}
-			s = a->sym;
-			t = s->type;
 			instoffset = 0;	// s.b. unused but just in case
 			return C_ADDR;
 
@@ -520,8 +515,6 @@ aclass(Adr *a)
 		switch(a->name) {
 		case D_EXTERN:
 		case D_STATIC:
-			s = a->sym;
-			t = s->type;
 			instoffset = 0;	// s.b. unused but just in case
 			return C_ADDR;
 		}
@@ -556,7 +549,6 @@ aclass(Adr *a)
 			s = a->sym;
 			if(s == S)
 				break;
-			t = s->type;
 			instoffset = 0;	// s.b. unused but just in case
 			return C_LCON;