diff --git a/arch/amd64/include/cflags.json b/arch/amd64/include/cflags.json
index d6037bd..5bffa44 100644
--- a/arch/amd64/include/cflags.json
+++ b/arch/amd64/include/cflags.json
@@ -8,6 +8,7 @@
 			"-mcmodel=small",
 			"-O0",
 			"-Wall",
+			"-Werror",
 			"-Wno-main",
 			"-Wno-missing-braces",
 			"-Wno-parentheses",
diff --git a/sys/include/libc.h b/sys/include/libc.h
index 40851a3..29d2f88 100644
--- a/sys/include/libc.h
+++ b/sys/include/libc.h
@@ -17,6 +17,7 @@
 #define	nelem(x)	(sizeof(x)/sizeof((x)[0]))
 #define	offsetof(s, m)	(uintptr_t)(&(((s*)0)->m))
 #define	assert(x)	if(x){}else jehanne__assert(#x)
+#define jehanne_getcallerpc()	((uintptr_t)__builtin_return_address(0))
 
 extern void (*_abort)(void);
 #define abort() if(_abort){_abort();}else{while(*(int*)0);}
@@ -324,7 +325,7 @@ extern	int	jehanne_enc16(char*, int, const uint8_t*, int);
 extern	int	jehanne_encodefmt(Fmt*);
 extern	void	jehanne_exits(const char*) __attribute__ ((noreturn));
 extern	double	jehanne_frexp(double, int*);
-extern	uintptr_t	jehanne_getcallerpc(void);
+//extern	uintptr_t	jehanne_getcallerpc(void);
 extern	int	jehanne_getfields(char*, char**, int, int, const char*);
 extern	int	jehanne_gettokens(char *, char **, int, const char *);
 extern	char*	jehanne_getuser(void);
diff --git a/sys/src/cmd/auth/newns.c b/sys/src/cmd/auth/newns.c
index a8b8d36..1cbd2e3 100644
--- a/sys/src/cmd/auth/newns.c
+++ b/sys/src/cmd/auth/newns.c
@@ -64,10 +64,10 @@ main(int argc, char **argv)
 		addns(getuser(), nsfile);
 	else
 		newns(getuser(), nsfile);
-	sys_exec(argv[0], argv);
+	sys_exec(argv[0], (const char **)argv);
 	if(!rooted(argv[0])){
 		rerrstr(err, sizeof err);
-		sys_exec(smprint("/cmd/%s", argv[0]), argv);
+		sys_exec(smprint("/cmd/%s", argv[0]), (const char **)argv);
 		sys_errstr(err, sizeof err);
 	}
 	sysfatal("exec: %s: %r", argv[0]);
diff --git a/sys/src/cmd/auth/none.c b/sys/src/cmd/auth/none.c
index 67ec4cf..ca1d98c 100644
--- a/sys/src/cmd/auth/none.c
+++ b/sys/src/cmd/auth/none.c
@@ -55,12 +55,12 @@ main(int argc, char *argv[])
 
 	if (argc > 0) {
 		strecpy(cmd, cmd+sizeof cmd, argv[0]);
-		sys_exec(cmd, &argv[0]);
+		sys_exec(cmd, (const char **)(&argv[0]));
 		if (strncmp(cmd, "/", 1) != 0
 		&& strncmp(cmd, "./", 2) != 0
 		&& strncmp(cmd, "../", 3) != 0) {
 			snprint(cmd, sizeof cmd, "/bin/%s", argv[0]);
-			sys_exec(cmd, &argv[0]);
+			sys_exec(cmd, (const char **)(&argv[0]));
 		}
 	} else {
 		strcpy(cmd, "/bin/rc");
diff --git a/sys/src/cmd/cpu.c b/sys/src/cmd/cpu.c
index 605195a..7acf15f 100644
--- a/sys/src/cmd/cpu.c
+++ b/sys/src/cmd/cpu.c
@@ -275,7 +275,7 @@ main(int argc, char **argv)
 		av[ac++] = patternfile;
 	}
 	av[ac] = nil;
-	sys_exec(exportfs, av);
+	sys_exec(exportfs, (const char **)av);
 	fatal(1, "starting exportfs");
 }
 
diff --git a/sys/src/cmd/ed.c b/sys/src/cmd/ed.c
index 86be702..d08e917 100644
--- a/sys/src/cmd/ed.c
+++ b/sys/src/cmd/ed.c
@@ -1043,7 +1043,7 @@ putline(void)
 }
 
 void
-blkio(int b, uint8_t *buf, int32_t (*iofcn)(int, void *, int32_t))
+blkio(int b, uint8_t *buf, long (*iofcn)(int, void *, int32_t))
 {
 	sys_seek(tfile, b*BLKSIZE, 0);
 	if((*iofcn)(tfile, buf, BLKSIZE) != BLKSIZE) {
@@ -1051,7 +1051,7 @@ blkio(int b, uint8_t *buf, int32_t (*iofcn)(int, void *, int32_t))
 	}
 }
 
-static int32_t
+static long
 writewrap(int a, void *b, int32_t c)
 {
 	return jehanne_write(a, (const void *)b, c);
diff --git a/sys/src/cmd/exportfs/exportfs.c b/sys/src/cmd/exportfs/exportfs.c
index 7ef7fe3..d22fbf4 100644
--- a/sys/src/cmd/exportfs/exportfs.c
+++ b/sys/src/cmd/exportfs/exportfs.c
@@ -947,7 +947,7 @@ filter(int fd, char *cmd)
 			fatal("filter: cannot dup to 0; %r\n");
 		sys_close(p[0]);
 		sys_close(p[1]);
-		sys_exec(file, argv);
+		sys_exec(file, (const char **)argv);
 		fatal("exec record module");
 	default:
 		sys_close(fd);
diff --git a/sys/src/cmd/exportfs/exportsrv.c b/sys/src/cmd/exportfs/exportsrv.c
index 111c0d2..08ea095 100644
--- a/sys/src/cmd/exportfs/exportsrv.c
+++ b/sys/src/cmd/exportfs/exportsrv.c
@@ -464,6 +464,8 @@ slave(Fsrpc *f)
 
 	if(readonly){
 		switch(f->work.type){
+		default:
+			break;
 		case Twrite:
 			reply(&f->work, &rhdr, Ereadonly);
 			f->busy = 0;
@@ -606,7 +608,7 @@ openmount(int sfd)
 	sys_close(1);
 	dup(p[0], 0);
 	dup(p[0], 1);
-	sys_exec("/cmd/exportfs", arg);
+	sys_exec("/cmd/exportfs", (const char**)arg);
 	sys__exits("whoops: exec failed");
 	return -1;
 }
diff --git a/sys/src/cmd/flip.c b/sys/src/cmd/flip.c
index ed2d129..ffe48fe 100644
--- a/sys/src/cmd/flip.c
+++ b/sys/src/cmd/flip.c
@@ -60,11 +60,11 @@ main(int argc, char **argv)
 			nargv[i] = argv[i];
 		}
 	}
-	sys_exec(*nargv, nargv);
+	sys_exec(*nargv, (const char **)nargv);
 	if(**nargv != '/' && strncmp(*nargv, "./", 2) != 0 &&
 			strncmp(*nargv, "../", 3) != 0){
 		*nargv = smprint("/cmd/%s", *nargv);
-		sys_exec(*nargv, nargv);
+		sys_exec(*nargv, (const char **)nargv);
 	}
 	sysfatal("exec: %r");
 }
diff --git a/sys/src/cmd/hmi/console/comconsole.c b/sys/src/cmd/hmi/console/comconsole.c
index 0152b82..9ad4777 100644
--- a/sys/src/cmd/hmi/console/comconsole.c
+++ b/sys/src/cmd/hmi/console/comconsole.c
@@ -88,7 +88,7 @@ main(int argc, char *argv[])
 		fd = sys_open("/dev/cons", OWRITE);
 		if(dup(fd, 2) != 2)
 			sysfatal("bad FDs: %r");
-		sys_exec(argv[1], argv+1);
+		sys_exec(argv[1], (const char**)(argv+1));
 		sysfatal("exec %s: %r", argv[1]);
 	}
 }
diff --git a/sys/src/cmd/import.c b/sys/src/cmd/import.c
index f24c831..1dc7ee2 100644
--- a/sys/src/cmd/import.c
+++ b/sys/src/cmd/import.c
@@ -249,7 +249,7 @@ main(int argc, char **argv)
 	sys_alarm(0);
 
 	if(backwards && argc > 1){
-		sys_exec(argv[1], &argv[1]);
+		sys_exec(argv[1], (const char **)&argv[1]);
 		sysfatal("exec: %r");
 	}
 	exits(0);
@@ -429,7 +429,7 @@ filter(int fd, char *cmd, char *host)
 		dup(p[0], 0);
 		sys_close(p[0]);
 		sys_close(p[1]);
-		sys_exec(file, argv);
+		sys_exec(file, (const char**)argv);
 		sysfatal("exec record module: %r");
 	default:
 		sys_close(fd);
diff --git a/sys/src/cmd/ip/ipconfig/ppp.c b/sys/src/cmd/ip/ipconfig/ppp.c
index b28a036..4bece4f 100644
--- a/sys/src/cmd/ip/ipconfig/ppp.c
+++ b/sys/src/cmd/ip/ipconfig/ppp.c
@@ -45,8 +45,8 @@ pppbinddev(void)
 			av[ac++] = conf.baud;
 		}
 		av[ac] = nil;
-		sys_exec("/bin/ip/ppp", av);
-		sys_exec("/ppp", av);
+		sys_exec("/bin/ip/ppp", (const char**)av);
+		sys_exec("/ppp", (const char**)av);
 		sysfatal("execing /ppp: %r");
 	}
 
diff --git a/sys/src/cmd/ip/listen1.c b/sys/src/cmd/ip/listen1.c
index 48ea14a..953fc19 100644
--- a/sys/src/cmd/ip/listen1.c
+++ b/sys/src/cmd/ip/listen1.c
@@ -124,9 +124,9 @@ main(int argc, char **argv)
 			dup(fd, 1);
 			dup(fd, 2);
 			sys_close(fd);
-			sys_exec(argv[1], argv+1);
+			sys_exec(argv[1], (const char **)(argv+1));
 			if(argv[1][0] != '/')
-				sys_exec(smprint("/cmd/%s", argv[1]), argv+1);
+				sys_exec(smprint("/cmd/%s", argv[1]), (const char**)(argv+1));
 			fprint(2, "%s: exec: %r\n", argv0);
 			exits(nil);
 		default:
diff --git a/sys/src/cmd/lock.c b/sys/src/cmd/lock.c
index 6486478..64cb7f3 100644
--- a/sys/src/cmd/lock.c
+++ b/sys/src/cmd/lock.c
@@ -134,10 +134,10 @@ main(int argc, char *argv[])
 			jehanne_fprint(fd, "%s%% ", lock);
 			sys_close(fd);
 		}
-		sys_exec(cmd, args);
+		sys_exec(cmd, (const char**)args);
 		if(cmd[0] != '/' && jehanne_strncmp(cmd, "./", 2) != 0 &&
 		   jehanne_strncmp(cmd, "../", 3) != 0)
-			sys_exec(jehanne_smprint("/cmd/%s", cmd), args);
+			sys_exec(jehanne_smprint("/cmd/%s", cmd), (const char**)args);
 		error(cmd);
 	}
 
diff --git a/sys/src/cmd/ns/clone.c b/sys/src/cmd/ns/clone.c
index c4288ff..76660c6 100644
--- a/sys/src/cmd/ns/clone.c
+++ b/sys/src/cmd/ns/clone.c
@@ -44,7 +44,7 @@ main(int argc, char *argv[])
 	args = &argv[2];
 	if(cmd[0] == '/' 
 	||(cmd[0] == '.' && (cmd[1] == '/' || (cmd[1] == '.' && cmd[2] == '/')))){
-		sys_exec(cmd, args);
+		sys_exec(cmd, (const char**)args);
 		sysfatal("exec %s failed: %r", cmd);
 	}
 
diff --git a/sys/src/cmd/rc/jehanne.c b/sys/src/cmd/rc/jehanne.c
index b1a9470..90536b7 100644
--- a/sys/src/cmd/rc/jehanne.c
+++ b/sys/src/cmd/rc/jehanne.c
@@ -331,7 +331,7 @@ Execute(word *args, word *path)
 			file[nc++] = '/';
 		}
 		memmove(file+nc, argv[1], mc);
-		sys_exec(file, argv+1);
+		sys_exec(file, (const char**)(argv+1));
 	}
 	rerrstr(file, sizeof file);
 	setstatus(file);
diff --git a/sys/src/cmd/sam/io.c b/sys/src/cmd/sam/io.c
index 48ab4f0..fb19f7c 100644
--- a/sys/src/cmd/sam/io.c
+++ b/sys/src/cmd/sam/io.c
@@ -195,7 +195,7 @@ bootterm(char *machine, char **argv)
 		sys_close(remotefd0);
 		sys_close(remotefd1);
 		argv[0] = "samterm";
-		sys_exec(samterm, argv);
+		sys_exec(samterm, (const char**)argv);
 		fprint(2, "can't exec: ");
 		perror(samterm);
 		sys__exits("damn");
@@ -211,7 +211,7 @@ bootterm(char *machine, char **argv)
 		sys_close(pt2h[0]);
 		sys_close(pt2h[1]);
 		argv[0] = "samterm";
-		sys_exec(samterm, argv);
+		sys_exec(samterm, (const char**)argv);
 		fprint(2, "can't exec: ");
 		perror(samterm);
 		sys__exits("damn");
@@ -263,7 +263,7 @@ connectto(char *machine, char **argv)
 		sys_close(p1[1]);
 		sys_close(p2[0]);
 		sys_close(p2[1]);
-		sys_exec(RXPATH, av);
+		sys_exec(RXPATH, (const char**)av);
 		dprint("can't exec %s\n", RXPATH);
 		exits("exec");
 
diff --git a/sys/src/cmd/srvfs.c b/sys/src/cmd/srvfs.c
index b5b1d37..62cc250 100644
--- a/sys/src/cmd/srvfs.c
+++ b/sys/src/cmd/srvfs.c
@@ -66,7 +66,7 @@ main(int argc, char **argv)
 		dup(pipefd[0], 1);
 		sys_close(pipefd[0]);
 		sys_close(pipefd[1]);
-		sys_exec(ename, arglist);
+		sys_exec(ename, (const char**)arglist);
 		fprint(2, "can't exec exportfs: %r\n");
 		exits("exec");
 	default:
diff --git a/sys/src/cmd/sys/ctrace.c b/sys/src/cmd/sys/ctrace.c
index c60213d..0866922 100644
--- a/sys/src/cmd/sys/ctrace.c
+++ b/sys/src/cmd/sys/ctrace.c
@@ -236,9 +236,9 @@ ParseArguments:
 			sysfatal("fork failed: %r");
 		if(pid == 0) {
 			jehanne_write(sys_open(smprint("/proc/%d/ctl", getpid()), OWRITE|OCEXEC), "hang", 4);
-			sys_exec(cmd, args);
+			sys_exec(cmd, (const char**)args);
 			if(cmd[0] != '/')
-				sys_exec(smprint("/cmd/%s", cmd), args);
+				sys_exec(smprint("/cmd/%s", cmd), (const char**)args);
 			sysfatal("exec %s failed: %r", cmd);
 		}
 	} else {
diff --git a/sys/src/cmd/time.c b/sys/src/cmd/time.c
index b1e62c3..18ca97f 100644
--- a/sys/src/cmd/time.c
+++ b/sys/src/cmd/time.c
@@ -33,11 +33,11 @@ main(int argc, char *argv[])
 	case -1:
 		error("fork");
 	case 0:
-		sys_exec(argv[1], &argv[1]);
+		sys_exec(argv[1], (const char**)&argv[1]);
 		if(argv[1][0] != '/' && jehanne_strncmp(argv[1], "./", 2) &&
 		   jehanne_strncmp(argv[1], "../", 3)){
 			jehanne_sprint(output, "/cmd/%s", argv[1]);
-			sys_exec(output, &argv[1]);
+			sys_exec(output, (const char**)&argv[1]);
 		}
 		error(argv[1]);
 	}
diff --git a/sys/src/cmd/xargs.c b/sys/src/cmd/xargs.c
index 4faca5a..bfbdfee 100644
--- a/sys/src/cmd/xargs.c
+++ b/sys/src/cmd/xargs.c
@@ -71,11 +71,11 @@ main(int argc, char **argv)
 		case -1:
 			sysfatal("fork: %r");
 		case 0:
-			sys_exec(*nargv, nargv);
+			sys_exec(*nargv, (const char**)nargv);
 			if(**nargv != '/' && strncmp(*nargv, "./", 2) != 0 &&
 					strncmp(*nargv, "../", 3) != 0){
 				*nargv = smprint("/cmd/%s", *nargv);
-				sys_exec(*nargv, nargv);
+				sys_exec(*nargv, (const char**)nargv);
 			}
 			sysfatal("exec: %r");
 		}
diff --git a/sys/src/kern/amd64/devvga.c b/sys/src/kern/amd64/devvga.c
index 8c669eb..1c72232 100644
--- a/sys/src/kern/amd64/devvga.c
+++ b/sys/src/kern/amd64/devvga.c
@@ -387,7 +387,7 @@ vgactl(Cmdbuf *cb)
 		deletescreenimage();
 		if(screensize(x, y, z, chan))
 			error(Egreg);
-		/* no break */
+		/* fall through */
 	case CMdrawinit:
 		if(scr->gscreen == nil)
 			error("drawinit: no gscreen");
diff --git a/sys/src/kern/amd64/usbohci.c b/sys/src/kern/amd64/usbohci.c
index 4180120..a999fbe 100644
--- a/sys/src/kern/amd64/usbohci.c
+++ b/sys/src/kern/amd64/usbohci.c
@@ -2068,7 +2068,7 @@ epopen(Ep *ep)
 		break;
 	case Tbulk:
 		ep->pollival = 1;	/* assume this; doesn't really matter */
-		/* and fall... */
+		/* fall through */
 	case Tintr:
 		io = ep->aux = smalloc(sizeof(Qio)*3);
 		io[OREAD].debug = io[OWRITE].debug = ep->debug;
diff --git a/sys/src/kern/ip/tcp.c b/sys/src/kern/ip/tcp.c
index 18441d2..4b03bf7 100644
--- a/sys/src/kern/ip/tcp.c
+++ b/sys/src/kern/ip/tcp.c
@@ -2255,6 +2255,7 @@ reset:
 			}
 			update(s, &seg);
 			tcpsetstate(s, Established);
+			/* fall through */
 		case Established:
 		case Close_wait:
 			update(s, &seg);
@@ -2291,6 +2292,7 @@ reset:
 				localclose(s, nil);
 				goto raise;
 			}
+			/* fall through */
 		case Time_wait:
 			tcb->flags |= FORCE;
 			if(tcb->timer.state != TcptimerON)
diff --git a/sys/src/kern/port/dev9p.c b/sys/src/kern/port/dev9p.c
index 236d069..5ee4433 100644
--- a/sys/src/kern/port/dev9p.c
+++ b/sys/src/kern/port/dev9p.c
@@ -824,6 +824,8 @@ mountio(Mnt *mnt, Mntrpc *r)
 		if(strcmp(up->errstr, Eintr) != 0 || waserror()){
 			r = mntflushfree(mnt, r);
 			switch(r->request.type){
+			default:
+				break;
 			case Tremove:
 			case Tclunk:
 				/* botch, abandon fid */
diff --git a/sys/src/kern/port/devcons.c b/sys/src/kern/port/devcons.c
index f2584b7..122faa1 100644
--- a/sys/src/kern/port/devcons.c
+++ b/sys/src/kern/port/devcons.c
@@ -202,7 +202,7 @@ addkbdq(Queue *q, int i)
 		kbdq = qopen(4*1024, 0, 0, 0);
 		if(kbdq == nil)
 			panic("no kbdq");
-		/* fall */
+		/* fall through */
 	default:
 		kickkbdq();
 	}
@@ -870,6 +870,7 @@ consread(Chan *c, void *buf, long n, int64_t off)
 				case '\n':
 				case 0x04:	/* ^D */
 					send = 1;
+					/* fall through */
 				default:
 					if(ch != 0x04)
 						kbd.line[kbd.x++] = ch;
diff --git a/sys/src/kern/port/devdraw.c b/sys/src/kern/port/devdraw.c
index 2488c35..41b5edc 100644
--- a/sys/src/kern/port/devdraw.c
+++ b/sys/src/kern/port/devdraw.c
@@ -1355,7 +1355,7 @@ drawwrite(Chan *c, void *a, long n, int64_t _)
 uint8_t*
 drawcoord(uint8_t *p, uint8_t *maxp, int oldx, int *newx)
 {
-	int b, x;
+	uint32_t b, x;
 
 	if(p >= maxp)
 		error(Eshortdraw);
@@ -1367,13 +1367,13 @@ drawcoord(uint8_t *p, uint8_t *maxp, int oldx, int *newx)
 		x |= *p++ << 7;
 		x |= *p++ << 15;
 		if(x & (1<<22))
-			x |= ~0<<23;
+			x |= ~0U<<23;
 	}else{
 		if(b & 0x40)
-			x |= ~0<<7;
+			x |= ~0U<<7;
 		x += oldx;
 	}
-	*newx = x;
+	*newx = (int)x;
 	return p;
 }
 
diff --git a/sys/src/kern/port/devmouse.c b/sys/src/kern/port/devmouse.c
index 8d218b5..b69e114 100644
--- a/sys/src/kern/port/devmouse.c
+++ b/sys/src/kern/port/devmouse.c
@@ -213,7 +213,7 @@ mouseopen(Chan *c, unsigned long omode)
 		mouse.lastcounter = mouse.counter;
 		mouse.resize = 0;
 		mousetime = seconds();
-		/* wet floor */
+		/* fall through */
 	case Qcursor:
 		incref(&mouse);
 	}
@@ -237,7 +237,7 @@ mouseclose(Chan *c)
 	case Qmouse:
 		mouse.open = 0;
 		mouseblankscreen(0);
-		/* wet floor */
+		/* fall through */
 	case Qcursor:
 		if(decref(&mouse) != 0)
 			return;
@@ -427,7 +427,7 @@ mousewrite(Chan *c, void *va, long n, int64_t _)
 
 		case CMblanktime:
 			blanktime = strtoul(cb->f[1], 0, 0);
-			/* wet floor */
+			/* fall through */
 		case CMtwitch:
 			mousetime = seconds();
 			mouseblankscreen(0);
diff --git a/sys/src/kern/port/devusb.c b/sys/src/kern/port/devusb.c
index 1bb8918..148604b 100644
--- a/sys/src/kern/port/devusb.c
+++ b/sys/src/kern/port/devusb.c
@@ -1079,7 +1079,7 @@ usbread(Chan *c, void *a, long n, int64_t offset)
 			n = nr;
 			break;
 		}
-		/* else fall */
+		/* else fall through */
 	default:
 		ddeprint("\nusbread q %#x fid %d cnt %ld off %lld\n",q,c->fid,n,offset);
 		n = ep->hp->epread(ep, a, n);
@@ -1445,7 +1445,7 @@ usbwrite(Chan *c, void *a, long n, int64_t off)
 			n = nr;
 			break;
 		}
-		/* else fall */
+		/* else fall through */
 	default:
 		ddeprint("\nusbwrite q %#x fid %d cnt %ld off %lld\n",q, c->fid, n, off);
 		ep->hp->epwrite(ep, a, n);
diff --git a/sys/src/kern/port/lib.h b/sys/src/kern/port/lib.h
index bd179ec..8fb0489 100644
--- a/sys/src/kern/port/lib.h
+++ b/sys/src/kern/port/lib.h
@@ -14,6 +14,7 @@
 #define nelem(x)	(sizeof(x)/sizeof((x)[0]))
 #define offsetof(s, m)	(uintptr_t)(&(((s*)0)->m))
 #define assert(x)	if(x){}else jehanne__assert(#x)
+#define getcallerpc()	((uintptr_t)__builtin_return_address(0))
 extern	void	jehanne__assert(const char*) __attribute__ ((noreturn));
 
 /*
@@ -179,7 +180,7 @@ extern	int	jehanne_dec16(uint8_t*, int, char*, int);
 extern	int	jehanne_enc16(char*, int, uint8_t*, int);
 extern	int	jehanne_encodefmt(Fmt*);
 extern	int	jehanne_dec64(uint8_t*, int, char*, int);
-#define	getcallerpc()	((uintptr_t)__builtin_return_address(0))
+//#define	getcallerpc()	((uintptr_t)__builtin_return_address(0))
 extern	int	jehanne_getfields(char*, char**, int, int, char*);
 extern	int	jehanne_gettokens(char *, char **, int, char *);
 extern	void	jehanne_qsort(void*, long, long, int (*)(void*, void*));
diff --git a/sys/src/kern/port/proc.c b/sys/src/kern/port/proc.c
index 9ae53a8..7cb79d9 100644
--- a/sys/src/kern/port/proc.c
+++ b/sys/src/kern/port/proc.c
@@ -1486,7 +1486,7 @@ procctl(Proc *p)
 	case Proc_traceme:
 		if(p->nnote == 0)
 			return;
-		/* No break */
+		/* fall through */
 
 	case Proc_stopme:
 		p->procctl = 0;
diff --git a/sys/src/kern/port/umem/segments.c b/sys/src/kern/port/umem/segments.c
index d30c854..373f55f 100644
--- a/sys/src/kern/port/umem/segments.c
+++ b/sys/src/kern/port/umem/segments.c
@@ -444,7 +444,7 @@ segment_release(ProcSegment** s)
 			if(segment->image > 1
 			||(up->parentpid == 1 && up->text[0] != '*'))
 				image_release(segment->image/NLOAD);
-			/* wet floor */
+			/* fall through */
 		case SgBSS:
 		case SgShared:
 		case SgStack:
diff --git a/sys/src/kern/port/usbehci.c b/sys/src/kern/port/usbehci.c
index 200dce5..b9a4a7b 100644
--- a/sys/src/kern/port/usbehci.c
+++ b/sys/src/kern/port/usbehci.c
@@ -2929,7 +2929,7 @@ epopen(Ep *ep)
 		break;
 	case Tbulk:
 		ep->pollival = 1;	/* assume this; doesn't really matter */
-		/* and fall... */
+		/* fall through */
 	case Tintr:
 		io = ep->aux = smalloc(sizeof(Qio)*3);
 		io[OREAD].debug = io[OWRITE].debug = ep->debug;
diff --git a/sys/src/lib/9p/req.c b/sys/src/lib/9p/req.c
index a6c9bc9..4e3acf0 100644
--- a/sys/src/lib/9p/req.c
+++ b/sys/src/lib/9p/req.c
@@ -12,8 +12,8 @@ increqref(void *v)
 
 	r = v;
 	if(r){
-if(chatty9p > 1)
-	fprint(2, "increfreq %p %ld\n", r, r->ref.ref);
+		if(chatty9p > 1)
+			fprint(2, "increfreq %p %ld\n", r, r->ref.ref);
 		incref(&r->ref);
 	}
 }
@@ -59,8 +59,8 @@ allocreq(Reqpool *pool, uint32_t tag)
 Req*
 lookupreq(Reqpool *pool, uint32_t tag)
 {
-if(chatty9p > 1)
-	fprint(2, "lookupreq %lud\n", tag);
+	if(chatty9p > 1)
+		fprint(2, "lookupreq %lud\n", tag);
 	return lookupkey(pool->map, tag);
 }
 
@@ -87,14 +87,12 @@ if(chatty9p > 1)
 		for(i=0; i<r->nflush; i++)
 			respond(r->flush[i], nil);
 		free(r->flush);
-		switch(r->ifcall.type){
-		case Tstat:
+		if(r->ifcall.type == Tstat){
 			free(r->ofcall.stat);
 			free(r->d.name);
 			free(r->d.uid);
 			free(r->d.gid);
 			free(r->d.muid);
-			break;
 		}
 		if(r->pool->destroy)
 			r->pool->destroy(r);
@@ -107,7 +105,7 @@ if(chatty9p > 1)
 Req*
 removereq(Reqpool *pool, uint32_t tag)
 {
-if(chatty9p > 1)
-	fprint(2, "removereq %lud\n", tag);
+	if(chatty9p > 1)
+		fprint(2, "removereq %lud\n", tag);
 	return deletekey(pool->map, tag);
 }
diff --git a/sys/src/lib/9p/srv.c b/sys/src/lib/9p/srv.c
index ffaffa7..8bc15e4 100644
--- a/sys/src/lib/9p/srv.c
+++ b/sys/src/lib/9p/srv.c
@@ -101,8 +101,8 @@ getreq(Srv *s)
 		r->type = 0;
 		r->srv = s;
 		r->pool = nil;
-if(chatty9p)
-	fprint(2, "<-%d- %F: dup tag\n", s->infd, &f);
+		if(chatty9p)
+			fprint(2, "<-%d- %F: dup tag\n", s->infd, &f);
 		return r;
 	}
 
@@ -113,11 +113,11 @@ if(chatty9p)
 	memset(&r->ofcall, 0, sizeof r->ofcall);
 	r->type = r->ifcall.type;
 
-if(chatty9p)
-	if(r->error)
-		fprint(2, "<-%d- %F: %s\n", s->infd, &r->ifcall, r->error);
-	else
-		fprint(2, "<-%d- %F\n", s->infd, &r->ifcall);
+	if(chatty9p)
+		if(r->error)
+			fprint(2, "<-%d- %F: %s\n", s->infd, &r->ifcall, r->error);
+		else
+			fprint(2, "<-%d- %F\n", s->infd, &r->ifcall);
 
 	return r;
 }
@@ -879,18 +879,45 @@ respond(Req *r, char *error)
 		if(rflush(r, error)<0)
 			return;
 		break;
-	case Tversion:	rversion(r, error);	break;
-	case Tauth:	rauth(r, error);	break;
-	case Tattach:	rattach(r, error);	break;
-	case Twalk:	rwalk(r, error);	break;
-	case Topen:	ropen(r, error);	break;
-	case Tcreate:	rcreate(r, error);	break;
-	case Tread:	rread(r, error);	break;
-	case Twrite:	rwrite(r, error);	break;
-	case Tclunk:	rclunk(r, error);	break;
-	case Tremove:	rremove(r, error, errbuf);	break;
-	case Tstat:	rstat(r, error);	break;
-	case Twstat:	rwstat(r, error);	break;
+	case Tversion:
+		rversion(r, error);
+		break;
+	case Tauth:
+		rauth(r, error);
+		break;
+	case Tattach:
+		rattach(r, error);
+		break;
+	case Twalk:
+		rwalk(r, error);
+		break;
+	case Topen:
+		ropen(r, error);
+		break;
+	case Tcreate:
+		rcreate(r, error);
+		break;
+	case Tread:
+		rread(r, error);
+		break;
+	case Twrite:
+		rwrite(r, error);
+		break;
+	case Tclunk:
+		rclunk(r, error);
+		break;
+	case Tremove:
+		rremove(r, error, errbuf);
+		break;
+	case Tstat:
+		rstat(r, error);
+		break;
+	case Twstat:
+		rwstat(r, error);
+		break;
+	default:
+		/* nothing to do */
+		break;
 	}
 
 	r->ofcall.tag = r->ifcall.tag;
@@ -898,8 +925,8 @@ respond(Req *r, char *error)
 	if(r->error)
 		setfcallerror(&r->ofcall, r->error);
 
-if(chatty9p)
-	fprint(2, "-%d-> %F\n", srv->outfd, &r->ofcall);
+	if(chatty9p)
+		fprint(2, "-%d-> %F\n", srv->outfd, &r->ofcall);
 
 	qlock(&srv->wlock);
 	n = convS2M(&r->ofcall, srv->wbuf, srv->msize);
diff --git a/sys/src/lib/auth/auth_getkey.c b/sys/src/lib/auth/auth_getkey.c
index ca0dd9b..fe8d46a 100644
--- a/sys/src/lib/auth/auth_getkey.c
+++ b/sys/src/lib/auth/auth_getkey.c
@@ -21,10 +21,11 @@ auth_getkey(char *params)
 		werrstr("auth_getkey: no /factotum or /boot/factotum: didn't get key %s", params);
 		return -1;
 	}
-if(0)	if(d->type != '/'){
-		werrstr("auth_getkey: /factotum may be bad: didn't get key %s", params);
-		return -1;
-	}
+	if(0)
+		if(d->type != '/'){
+			werrstr("auth_getkey: /factotum may be bad: didn't get key %s", params);
+			return -1;
+		}
 	switch(pid = fork()){
 	case -1:
 		werrstr("can't fork for %s: %r", name);
diff --git a/sys/src/lib/jehanne/build.json b/sys/src/lib/jehanne/build.json
index 98d9267..b1b9b03 100644
--- a/sys/src/lib/jehanne/build.json
+++ b/sys/src/lib/jehanne/build.json
@@ -147,7 +147,6 @@
 			"port/fmod.c",
 			"port/frand.c",
 			"port/frexp.c",
-			"port/getcallerpc.c",
 			"port/getfields.c",
 			"port/getuser.c",
 			"port/hangup.c",
diff --git a/sys/src/lib/jehanne/klibc.json b/sys/src/lib/jehanne/klibc.json
index 35a6853..9c05fe2 100644
--- a/sys/src/lib/jehanne/klibc.json
+++ b/sys/src/lib/jehanne/klibc.json
@@ -64,7 +64,6 @@
 			"port/fmod.c",
 			"port/frand.c",
 			"port/frexp.c",
-			"port/getcallerpc.c",
 			"port/getfields.c",
 			"port/hypot.c",
 			"port/lnrand.c",
diff --git a/sys/src/lib/jehanne/port/getcallerpc.c b/sys/src/lib/jehanne/port/getcallerpc.c
deleted file mode 100644
index ab2c9a3..0000000
--- a/sys/src/lib/jehanne/port/getcallerpc.c
+++ /dev/null
@@ -1,17 +0,0 @@
-/*
- * This file is part of the UCB release of Plan 9. It is subject to the license
- * terms in the LICENSE file found in the top-level directory of this
- * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
- * part of the UCB release of Plan 9, including this file, may be copied,
- * modified, propagated, or distributed except according to the terms contained
- * in the LICENSE file.
- */
-
-#include <u.h>
-#include <libc.h>
-
-uintptr_t
-jehanne_getcallerpc(void)
-{
-	return (uintptr_t)__builtin_return_address(2);
-}
diff --git a/sys/src/lib/memlayer/draw.c b/sys/src/lib/memlayer/draw.c
index 8b22975..629a403 100644
--- a/sys/src/lib/memlayer/draw.c
+++ b/sys/src/lib/memlayer/draw.c
@@ -13,6 +13,8 @@
 #include <memdraw.h>
 #include <memlayer.h>
 
+#define DBG if(drawdebug)
+
 struct Draw
 {
 	Point	deltas;
@@ -66,14 +68,13 @@ memdraw(Memimage *dst, Rectangle r, Memimage *src, Point p0, Memimage *mask, Poi
 	Rectangle srcr, tr, mr;
 	Memlayer *dl, *sl;
 
-	if(drawdebug)
-		iprint("memdraw %p %R %p %P %p %P\n", dst, r, src, p0, mask, p1);
+	DBG iprint("memdraw %p %R %p %P %p %P\n", dst, r, src, p0, mask, p1);
 
 	if(mask == nil)
 		mask = memopaque;
 
 	if(mask->layer){
-if(drawdebug)	iprint("mask->layer != nil\n");
+		DBG iprint("mask->layer != nil\n");
 		return;	/* too hard, at least for now */
 	}
 
@@ -84,7 +85,7 @@ if(drawdebug)	iprint("mask->layer != nil\n");
 	}
 
 	if(drawclip(dst, &r, src, &p0, mask, &p1, &srcr, &mr) == 0){
-if(drawdebug)	iprint("drawclip dstcr %R srccr %R maskcr %R\n", dst->clipr, src->clipr, mask->clipr);
+		DBG iprint("drawclip dstcr %R srccr %R maskcr %R\n", dst->clipr, src->clipr, mask->clipr);
 		return;
 	}
 
diff --git a/sys/src/lib/thread/main.c b/sys/src/lib/thread/main.c
index 20f92e2..c2ba893 100644
--- a/sys/src/lib/thread/main.c
+++ b/sys/src/lib/thread/main.c
@@ -79,7 +79,7 @@ efork(Execargs *e)
 
 	_threaddebug(DBGEXEC, "_schedexec %s", e->prog);
 	sys_close(e->fd[0]);
-	sys_exec(e->prog, e->args);
+	sys_exec(e->prog, (const char **)e->args);
 	_threaddebug(DBGEXEC, "_schedexec failed: %r");
 	jehanne_rerrstr(buf, sizeof buf);
 	if(buf[0]=='\0')