diff --git a/unix/Makefile b/unix/Makefile
index 920e767..801a801 100644
--- a/unix/Makefile
+++ b/unix/Makefile
@@ -2,12 +2,13 @@
 ifeq ($(OS),Linux)
 PRGLIBS=-lrt
 SOLIBS=-ldl -lrt
-else
-LIBS=
+endif
+ifeq ($(OS),Darwin)
+PRGLIBS=
 SOLIBS=
-endif	
+endif
 
-CC=cc -D_GNU_SOURCE -D_BSD_SOURCE=1 -std=c99 -Wall -O3
+CC=cc -D_GNU_SOURCE -D_BSD_SOURCE=1 -std=c99 -Wall -O2 -fomit-frame-pointer -fno-stack-protector -Wno-incompatible-pointer-types 
 
 all: fsatrace fsatrace.so
 
diff --git a/unix/fsatrace.c b/unix/fsatrace.c
index 2ad695c..fe90f1d 100644
--- a/unix/fsatrace.c
+++ b/unix/fsatrace.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <stdarg.h>
 #include <fcntl.h>
 #include <limits.h>
 #include "fsatrace.h"
@@ -24,8 +25,8 @@
 		fd = 1;
 	if (fd < 0)
 		fprintf(stderr, "Unable to open output file '%s'\n", path);
-	sz = *(size_t *) p;
-	r = write(fd, p + sizeof(size_t), sz);
+	sz = (size_t) * (unsigned *)p;
+	r = write(fd, p + sizeof(unsigned), sz);
 	assert(r == sz);
 	if (fd != 1)
 		close(fd);
@@ -34,11 +35,21 @@
 unsigned long
 hash(unsigned char *str)
 {
-  unsigned long h = 5381;
-  int c;
-  while ((c = *str++))
-    h = ((h << 5) + h) + c;
-  return h;
+	unsigned long	h = 5381;
+	int		c;
+	while ((c = *str++))
+		h = ((h << 5) + h) + c;
+	return h;
+}
+
+static void
+fatal(const char *fmt,...)
+{
+	va_list		ap;
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	exit(EXIT_FAILURE);
 }
 
 int
@@ -52,10 +63,8 @@
 	int		rc = EXIT_FAILURE;
 	int		child;
 	const char     *out;
-	if (argc < 4 || strcmp(argv[2], "--")) {
-		fprintf(stderr, "Usage: %s <output> -- <cmdline>\n", argv[0]);
-		return rc;
-	}
+	if (argc < 4 || strcmp(argv[2], "--"))
+		fatal("Usage: %s <output> -- <cmdline>\n", argv[0]);
 	out = argv[1];
 	snprintf(shname, sizeof(shname), "/%ld", hash((unsigned char *)out));
 	for (size_t i = 0, l = strlen(shname); i < l; i++)
@@ -66,23 +75,24 @@
 	r = ftruncate(fd, LOGSZ);
 	assert(!r);
 	buf = mmap(0, LOGSZ, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
-	snprintf(so, sizeof(so), "%s.so", argv[0]);
 #ifdef __APPLE__
+	snprintf(so, sizeof(so), "%s.dylib", argv[0]);
 	setenv("DYLD_INSERT_LIBRARIES", so, 1);
 	setenv("DYLD_FORCE_FLAT_NAMESPACE", "1", 1);
 #else
+	snprintf(so, sizeof(so), "%s.so", argv[0]);
 	setenv("LD_PRELOAD", so, 1);
 #endif
 	setenv(ENVOUT, shname, 1);
 	child = fork();
 	if (!child) {
 		execvp(argv[3], argv + 3);
-		assert(0);
+		fatal("Unable to execute command '%s'\n", argv[3]);
 	}
 	r = wait(&rc);
 	assert(r >= 0);
 	rc = WEXITSTATUS(rc);
-	if (!rc)
+	if (!rc || *out == '-')
 		dump(out, buf);
 	munmap(buf, LOGSZ);
 	close(fd);
diff --git a/unix/fsatraceso.c b/unix/fsatraceso.c
index 94cf27a..abb4edd 100644
--- a/unix/fsatraceso.c
+++ b/unix/fsatraceso.c
@@ -34,34 +34,6 @@
 static char    *s_buf;
 static const int wmode = O_RDWR | O_WRONLY | O_APPEND | O_CREAT | O_TRUNC;
 
-static int
-good(const char *s, int sz)
-{
-	int		i;
-	int		bad = 0;
-
-	for (i = 0; i < sz; i++)
-		bad += s[i] == 0;
-	return !bad;
-}
-
-static void
-swrite(const char *p, int sz)
-{
-	int		g;
-	char           *dst = s_buf + sizeof(size_t);
-	size_t         *psofar = (size_t *) s_buf;
-	size_t		sofar;
-	if (!s_buf)
-		return;
-	sofar = __sync_fetch_and_add(psofar, sz);
-	memcpy(dst + sofar, p, sz);
-	g = good(p, sz);
-	if (!g)
-		fprintf(stderr, "BAD: %s\n", p);
-	assert(g);
-}
-
 static void
 __attribute((constructor(101)))
 init()
@@ -81,35 +53,63 @@
 }
 
 static inline void
+__attribute((noinline))
 iemit(int c, const char *p1, const char *p2)
 {
-	char		buf       [10000];
-	int		sz = 0;
-
-	sz += snprintf(buf, sizeof(buf) - 1 - sz, "%c|%s", c, p1);
-	if (p2)
-		sz += snprintf(buf + sz, sizeof(buf) - 1 - sz, "|%s", p2);
-	sz += snprintf(buf + sz, sizeof(buf) - 1 - sz, "\n");
-	assert(sz < sizeof(buf) - 1);
-	buf[sz] = 0;
-	swrite(buf, sz);
+	char           *dst = s_buf + sizeof(unsigned);
+	unsigned       *psofar = (unsigned *)s_buf;
+	unsigned	sofar;
+	unsigned	sz;
+	unsigned	s1;
+	unsigned	s2;
+	char           *p;
+	if (!s_buf)
+		return;
+	s1 = strlen(p1);
+	sz = s1 + 3;
+	if (p2) {
+		s2 = strlen(p2);
+		sz += s2 + 1;
+	}
+	sofar = __sync_fetch_and_add(psofar, sz);
+	p = dst + sofar;
+	*p++ = c;
+	*p++ = '|';
+	memcpy(p, p1, s1);
+	p += s1;
+	if (p2) {
+		*p++ = '|';
+		memcpy(p, p2, s2);
+		p += s2;
+	}
+	*p++ = '\n';
 }
 
 static void
+__attribute((noinline))
 emit(int c, const char *p1)
 {
 	char		ap        [PATH_MAX];
 	iemit(c, realpath(p1, ap), 0);
 }
 
+static void
+__attribute((noinline))
+resolv(void ** p, const char * n) {
+  if (!*p)
+    *p = dlsym(RTLD_NEXT, n);
+  assert(*p);
+}
+
+#define R(f) resolv((void**)&o##f, #f)
+
 FILE           *
 fopen(const char *p, const char *m)
 {
 	FILE           *r;
 	static FILE    *(*ofopen) (const char *, const char *)= 0;
-	if (!ofopen)
-		ofopen = dlsym(RTLD_NEXT, "fopen");
-	assert(ofopen);
+	//	resolv(&ofopen, "fopen");
+	R(fopen);
 	r = ofopen(p, m);
 	if (r)
 		emit(strchr(m, 'r') ? 'r' : 'w', p);
@@ -121,9 +121,7 @@
 {
 	FILE           *r;
 	static FILE    *(*ofopen64) (const char *, const char *)= 0;
-	if (!ofopen64)
-		ofopen64 = dlsym(RTLD_NEXT, "fopen64");
-	assert(ofopen64);
+	R(fopen64);
 	r = ofopen64(p, m);
 	if (r)
 		emit(strchr(m, 'r') ? 'r' : 'w', p);
@@ -135,9 +133,7 @@
 {
 	int		r;
 	static int      (*oopen) (const char *, int, mode_t)= 0;
-	if (!oopen)
-		oopen = dlsym(RTLD_NEXT, "open");
-	assert(oopen);
+	R(open);
 	r = oopen(p, f, m);
 	if (r >= 0)
 		emit(f & wmode ? 'w' : 'r', p);
@@ -149,9 +145,7 @@
 {
 	int		r;
 	static int      (*oopen64) (const char *, int, mode_t)= 0;
-	if (!oopen64)
-		oopen64 = dlsym(RTLD_NEXT, "open64");
-	assert(oopen64);
+	R(open64);
 	r = oopen64(p, f, m);
 	if (r >= 0)
 		emit(f & wmode ? 'w' : 'r', p);
@@ -164,14 +158,11 @@
 	int		r;
 	if (fd != AT_FDCWD) {
 		static int      (*oopenat) (int, const char *, int, mode_t)= 0;
-		if (!oopenat)
-			oopenat = dlsym(RTLD_NEXT, "openat");
-		assert(oopenat);
+		R(openat);
 		r = oopenat(fd, p, f, m);
 		if (r >= 0)
 			iemit(f & wmode ? 'W' : 'R', p, 0);
-	}
-	else
+	} else
 		r = open(p, f, m);
 	return r;
 }
@@ -182,14 +173,11 @@
 	int		r;
 	if (fd != AT_FDCWD) {
 		static int      (*oopenat64) (int, const char *, int, mode_t)= 0;
-		if (!oopenat64)
-			oopenat64 = dlsym(RTLD_NEXT, "openat64");
-		assert(oopenat64);
+		R(openat64);
 		r = oopenat64(fd, p, f, m);
 		if (r >= 0)
 			iemit(f & wmode ? 'W' : 'R', p, 0);
-	}
-	else
+	} else
 		r = open64(p, f, m);
 	return r;
 }
@@ -202,9 +190,7 @@
 	char		b2        [PATH_MAX];
 	char           *rp1 = realpath(p1, b1);
 	static int      (*orename) (const char *, const char *)= 0;
-	if (!orename)
-		orename = dlsym(RTLD_NEXT, "rename");
-	assert(orename);
+	R(rename);
 	r = orename(p1, p2);
 	if (!r)
 		iemit('m', realpath(p2, b2), rp1);
@@ -217,14 +203,11 @@
 	int		r;
 	if (fd1 != AT_FDCWD || fd2 != AT_FDCWD) {
 		static int      (*orenameat) (const char *, const char *)= 0;
-		if (!orenameat)
-			orenameat = dlsym(RTLD_NEXT, "renameat");
-		assert(orenameat);
+		R(renameat);
 		r = orenameat(p1, p2);
 		if (!r)
 			iemit('R', p2, p1);
-	} 
-	else
+	} else
 		r = rename(p1, p2);
 	return r;
 }
@@ -236,9 +219,7 @@
 	char		b         [PATH_MAX];
 	char           *rp = realpath(p, b);
 	static int      (*ounlink) (const char *)= 0;
-	if (!ounlink)
-		ounlink = dlsym(RTLD_NEXT, "unlink");
-	assert(ounlink);
+	R(unlink);
 	r = ounlink(p);
 	if (!r)
 		iemit('d', rp, 0);
@@ -251,15 +232,12 @@
 	int		r;
 	if (fd != AT_FDCWD) {
 		static int      (*ounlinkat) (int fd, const char *p, int f);
-		if (!ounlinkat)
-			ounlinkat = dlsym(RTLD_NEXT, "unlinkat");
-		assert(ounlinkat);
+		R(unlinkat);
 		r = ounlinkat(fd, p, f);
 		if (!r)
 			iemit('D', p, 0);
 		assert(0);
-	} 
-	else if (f & AT_REMOVEDIR)
+	} else if (f & AT_REMOVEDIR)
 		r = rmdir(p);
 	else
 		r = unlink(p);