diff --git a/SConstruct b/SConstruct
index 8f68832a8b419ebd57a7ed9bc6d9668b3be751cf..9f468c2f04eca99f3fb2a7807d66742e57b6c51e 100644
--- a/SConstruct
+++ b/SConstruct
@@ -2,7 +2,10 @@
 import os
 env = Environment()
 
-env.MergeFlags("-std=gnu99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-attributes -lrt")
+env.MergeFlags("-std=gnu99 -Wall -Wextra -Werror -Wno-unused-parameter -Wno-attributes")
+
+if not env['PLATFORM'] == 'darwin':
+    env.MergeFlags("-lrt")
 
 AddOption("--variant",
           dest="variant",
@@ -37,7 +40,7 @@ if GetOption("coverage"):
                LDFLAGS=["-fprofile-arcs", "-ftest-coverage"],
                LIBS=['gcov'])
 
-if os.getenv("CC") == "clang":
+if os.getenv("CC") == "clang" or env['PLATFORM'] == 'darwin':
     env.Replace(CC="clang",
                 CXX="clang++")
 Export('env')
diff --git a/src/backends/regex_debug.c b/src/backends/regex_debug.c
index 7319e3fd163c1df7fc9e73236dbc9ba6fd827015..5ca6ca42624a8149eb472e5fabaac59ca1ec248d 100644
--- a/src/backends/regex_debug.c
+++ b/src/backends/regex_debug.c
@@ -1,7 +1,7 @@
 // Intended to be included from regex_debug.c
 #define _GNU_SOURCE
 #include <stdio.h>
-#include <malloc.h>
+#include <stdlib.h>
 
 
 
diff --git a/src/benchmark.c b/src/benchmark.c
index d81d2f81ddd5e922b2df7bf434408aad614696f2..4f7b78a8a63a74b516f3779b149da0b179142951 100644
--- a/src/benchmark.c
+++ b/src/benchmark.c
@@ -4,6 +4,29 @@
 #include "hammer.h"
 #include "internal.h"
 
+#ifdef __MACH__
+#include <mach/clock.h>
+#include <mach/mach.h>
+#endif
+
+void h_benchmark_clock_gettime(struct timespec *ts) {
+#ifdef __MACH__ // OS X does not have clock_gettime, use clock_get_time
+  /* 
+   * This returns real time, not CPU time. See http://stackoverflow.com/a/6725161
+   * Possible solution: http://stackoverflow.com/a/11659289
+   */
+  clock_serv_t cclock;
+  mach_timespec_t mts;
+  host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
+  clock_get_time(cclock, &mts);
+  mach_port_deallocate(mach_task_self(), cclock);
+  ts->tv_sec = mts.tv_sec;
+  ts->tv_nsec = mts.tv_nsec;
+#else
+  clock_gettime(CLOCK_THREAD_CPUTIME_ID, ts);
+#endif
+}
+
 /*
   Usage:
   Create your parser (i.e., const HParser*), and an array of test cases
@@ -88,12 +111,12 @@ HBenchmarkResults *h_benchmark__m(HAllocator* mm__, HParser* parser, HParserTest
       long long time_diff;
       do {
 	count *= 2; // Yes, this means that the first run will run the function twice. This is fine, as we want multiple runs anyway.
-	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts_start);
+  h_benchmark_clock_gettime(&ts_start);
 	for (cur = 0; cur < count; cur++) {
 	  h_parse_result_free(h_parse(parser, tc->input, tc->length));
 	}
-	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts_end);
-	
+  h_benchmark_clock_gettime(&ts_end);
+
 	// time_diff is in ns
 	time_diff = (ts_end.tv_sec - ts_start.tv_sec) * 1000000000 + (ts_end.tv_nsec - ts_start.tv_nsec);
       } while (time_diff < 100000000);
diff --git a/src/pprint.c b/src/pprint.c
index d8b22e2d2fa1d317db15334b70021696c054dd9d..b314a9f36a527f365b706d59c3ee7ff5b535540f 100644
--- a/src/pprint.c
+++ b/src/pprint.c
@@ -21,6 +21,7 @@
 #include "hammer.h"
 #include "internal.h"
 #include <stdlib.h>
+#include <inttypes.h>
 
 typedef struct pp_state {
   int delta;
@@ -49,13 +50,13 @@ void h_pprint(FILE* stream, const HParsedToken* tok, int indent, int delta) {
     break;
   case TT_SINT:
     if (tok->sint < 0)
-      fprintf(stream, "%*ss -%#lx\n", indent, "", -tok->sint);
+      fprintf(stream, "%*ss -%#" PRIx64 "\n", indent, "", -tok->sint);
     else
-      fprintf(stream, "%*ss %#lx\n", indent, "", tok->sint);
+      fprintf(stream, "%*ss %#" PRIx64 "\n", indent, "", tok->sint);
       
     break;
   case TT_UINT:
-    fprintf(stream, "%*su %#lx\n", indent, "", tok->uint);
+    fprintf(stream, "%*su %#" PRIx64 "\n", indent, "", tok->uint);
     break;
   case TT_SEQUENCE: {
     fprintf(stream, "%*s[\n", indent, "");
@@ -128,14 +129,14 @@ static void unamb_sub(const HParsedToken* tok, struct result_buf *buf) {
     break;
   case TT_SINT:
     if (tok->sint < 0)
-      len = asprintf(&tmpbuf, "s-%#lx", -tok->sint);
+      len = asprintf(&tmpbuf, "s-%#" PRIx64, -tok->sint);
     else
-      len = asprintf(&tmpbuf, "s%#lx", tok->sint);
+      len = asprintf(&tmpbuf, "s%#" PRIx64, tok->sint);
     append_buf(buf, tmpbuf, len);
     free(tmpbuf);
     break;
   case TT_UINT:
-    len = asprintf(&tmpbuf, "u%#lx", tok->uint);
+    len = asprintf(&tmpbuf, "u%#" PRIx64, tok->uint);
     append_buf(buf, tmpbuf, len);
     free(tmpbuf);
     break;