diff --git a/src/cmd/6c/list.c b/src/cmd/6c/list.c
index 094f5a2064..e3a0ea81b4 100644
--- a/src/cmd/6c/list.c
+++ b/src/cmd/6c/list.c
@@ -92,7 +92,7 @@ Pconv(Fmt *fp)
 			p->as, &p->from, &p->to);
 		break;
 
-	defaul:
+	default:
 		sprint(str, "	%A	%D,%lD", p->as, &p->from, &p->to);
 		break;
 	}
diff --git a/src/cmd/ar/ar.c b/src/cmd/ar/ar.c
index 323103bcb1..aeccc8e573 100644
--- a/src/cmd/ar/ar.c
+++ b/src/cmd/ar/ar.c
@@ -779,7 +779,6 @@ int
 duplicate(char *name)
 {
 	Hashchain *p;
-	char *cp;
 	int h;
 
 	h = hashstr(name) % NHASH;
@@ -1602,8 +1601,7 @@ parsepkgdata(char **pp, char *ep, int *exportp, char **prefixp, char **namep, ch
 int
 parsemethod(char **pp, char *ep, char **methp)
 {
-	char *p, *prefix, *name, *def;
-	int n;
+	char *p;
 	
 	// skip white space
 	p = *pp;
@@ -1664,16 +1662,15 @@ strappend(char *s, char *t)
 void
 getpkgdef(char **datap, int *lenp)
 {
-	Fmt f;
 	int i, j, len;
-	char *data, *p, *ep;
+	char *data, *p;
 	Import **all, *x;
 
 	// make a list of all the exports and count string sizes
 	all = armalloc(nimport*sizeof all[0]);
 	j = 0;
 	len = 7 + 3 + strlen(pkgstmt) + 1;	// import\n$$\npkgstmt\n
-	for(i=0; i<NHASH; i++) {
+	for(i=0; i<NIHASH; i++) {
 		for(x=ihash[i]; x; x=x->hash) {
 			all[j++] = x;
 			len += strlen(x->prefix) + 1
diff --git a/src/cmd/gc/dcl.c b/src/cmd/gc/dcl.c
index 95f4e020cb..7eed70e807 100644
--- a/src/cmd/gc/dcl.c
+++ b/src/cmd/gc/dcl.c
@@ -1120,7 +1120,7 @@ defercheckwidth(void)
 void
 resumecheckwidth(void)
 {
-	TypeList *l, *next;
+	TypeList *l;
 
 	if(!defercalc)
 		fatal("restartcheckwidth");
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index c086aeb854..3953ca20c1 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -1351,7 +1351,6 @@ wnames[] =
 int
 Wconv(Fmt *fp)
 {
-	char buf[500];
 	int w;
 
 	w = va_arg(fp->args, int);
diff --git a/src/libmach_amd64/8db.c b/src/libmach_amd64/8db.c
index d4ee633ff4..040dd1e861 100644
--- a/src/libmach_amd64/8db.c
+++ b/src/libmach_amd64/8db.c
@@ -1364,7 +1364,7 @@ igetl(Map *map, Instr *ip, uint32 *lp)
 
 /*
  *  get 8 bytes of the instruction
- */
+ *
 static int
 igetq(Map *map, Instr *ip, vlong *qp)
 {
@@ -1380,6 +1380,7 @@ igetq(Map *map, Instr *ip, vlong *qp)
 	*qp = q;
 	return 1;
 }
+ */
 
 static int
 getdisp(Map *map, Instr *ip, int mod, int rm, int code, int pcrel)
@@ -1958,11 +1959,11 @@ pea(Instr *ip)
 {
 	if (ip->mod == 3) {
 		if (ip->osize == 'B')
-			bprint(ip, (ip->rex & REXB? breg64: breg)[ip->base]);
+			bprint(ip, (ip->rex & REXB? breg64: breg)[(uchar)ip->base]);
 		else if(ip->rex & REXB)
 			bprint(ip, "%s%s", ANAME(ip), reg[ip->base+8]);
 		else
-			bprint(ip, "%s%s", ANAME(ip), reg[ip->base]);
+			bprint(ip, "%s%s", ANAME(ip), reg[(uchar)ip->base]);
 		return;
 	}
 	if (ip->segment)
diff --git a/src/libmach_amd64/darwin.c b/src/libmach_amd64/darwin.c
index f210f25a94..e9e9bddc70 100644
--- a/src/libmach_amd64/darwin.c
+++ b/src/libmach_amd64/darwin.c
@@ -24,6 +24,7 @@
 #include <sys/ptrace.h>
 #include <sys/signal.h>
 #include <mach/mach.h>
+#include <mach/mach_traps.h>
 #include <errno.h>
 #include <libc.h>
 #include <bio.h>
@@ -31,6 +32,8 @@
 #include <ureg_amd64.h>
 typedef struct Ureg Ureg;
 
+extern mach_port_t mach_reply_port(void);	// should be in system headers, is not
+
 // Mach-error wrapper.
 // Takes a mach return code and converts it into 0 / -1,
 // setting errstr when it returns -1.
@@ -197,7 +200,7 @@ enum {
 static Thread*
 addpid(int pid, int force)
 {
-	int i, j, r;
+	int i, j;
 	mach_port_t task;
 	mach_port_t *thread;
 	uint nthread;
@@ -276,6 +279,7 @@ idtotable(int id)
 	return &thr[id];
 }
 
+/*
 static int
 idtopid(int id)
 {
@@ -285,6 +289,7 @@ idtopid(int id)
 		return -1;
 	return t->pid;
 }
+*/
 
 static mach_port_t
 idtotask(int id)
@@ -388,7 +393,6 @@ proctextfile(int pid)
 static int
 machsegrw(Map *map, Seg *seg, uvlong addr, void *v, uint n, int isr)
 {
-	uintptr nn;
 	mach_port_t task;
 	int r;
 
@@ -397,6 +401,7 @@ machsegrw(Map *map, Seg *seg, uvlong addr, void *v, uint n, int isr)
 		return -1;
 
 	if(isr){
+		vm_size_t nn;
 		nn = n;
 		if(me(vm_read_overwrite(task, addr, n, (uintptr)v, &nn)) < 0)
 			return -1;
@@ -477,7 +482,7 @@ machregrw(Map *map, Seg *seg, uvlong addr, void *v, uint n, int isr)
 {
 	uint nn;
 	mach_port_t thread;
-	int reg, r;
+	int reg;
 	union {
 		x86_thread_state64_t regs;
 		uchar p[1];
@@ -547,7 +552,6 @@ threadstopped(Thread *t)
 {
 	struct thread_basic_info info;
 	uint size;
-	int r;
 
 	size = sizeof info;
 	if(me(thread_info(t->thread, THREAD_BASIC_INFO, (thread_info_t)&info, &size)) <  0){
@@ -568,7 +572,7 @@ threadstart(Thread *t, int singlestep)
 	x86_thread_state64_t regs;
 
 	if(!threadstopped(t))
-		return;
+		return 0;
 
 	// Set or clear the processor single-step flag, as appropriate.
 	n = x86_THREAD_STATE64_COUNT;
@@ -667,7 +671,7 @@ int
 ctlproc(int id, char *msg)
 {
 	Thread *t;
-	int status, r;
+	int status;
 
 	// Hang/attached dance is for debugging newly exec'ed programs.
 	// After fork, the child does ctlproc("hang") before exec,
diff --git a/src/libmach_amd64/linux.c b/src/libmach_amd64/linux.c
index ff4012081b..4fb5d49ba3 100644
--- a/src/libmach_amd64/linux.c
+++ b/src/libmach_amd64/linux.c
@@ -30,6 +30,7 @@
 #include <u.h>
 #include <sys/ptrace.h>
 #include <sys/signal.h>
+#include <sys/wait.h>
 #include <errno.h>
 #include <libc.h>
 #include <bio.h>
@@ -132,9 +133,7 @@ ptraceattach(int pid)
 Map*
 attachproc(int pid, Fhdr *fp)
 {
-	char buf[64];
 	Map *map;
-	vlong n;
 
 	if(ptraceattach(pid) < 0)
 		return nil;
@@ -264,7 +263,7 @@ procnotes(int pid, char ***pnotes)
 int
 ctlproc(int pid, char *msg)
 {
-	int i, p, status;
+	int i;
 
 	if(strcmp(msg, "attached") == 0){
 		for(i=0; i<nattached; i++)
diff --git a/src/libmach_amd64/map.c b/src/libmach_amd64/map.c
index eb7eaf9990..747969335f 100644
--- a/src/libmach_amd64/map.c
+++ b/src/libmach_amd64/map.c
@@ -80,6 +80,7 @@ setmap(Map *map, int fd, uvlong b, uvlong e, vlong f, char *name, Maprw *rw)
 	return 1;
 }
 
+/*
 static uvlong
 stacktop(int pid)
 {
@@ -110,6 +111,7 @@ stacktop(int pid)
 		return 0;
 	return strtoull(cp, 0, 16);
 }
+*/
 
 int
 findseg(Map *map, char *name)