diff --git a/libc/bionic/clock.cpp b/libc/bionic/clock.cpp
index a2636c6..053e9e7 100644
--- a/libc/bionic/clock.cpp
+++ b/libc/bionic/clock.cpp
@@ -30,12 +30,13 @@
 #include <sys/sysconf.h>
 #include <sys/times.h>
 
+#include "private/bionic_constants.h"
+
 // http://pubs.opengroup.org/onlinepubs/9699919799/functions/clock.html
 clock_t clock() {
-  tms t;
-  times(&t);
-  // Although times(2) and clock(3) both use the type clock_t, the units are
-  // different. For times(2) it's pure clock ticks, but for clock(3) the unit
-  // is CLOCKS_PER_SEC, so we need to scale appropriately.
-  return (t.tms_utime + t.tms_stime) * (CLOCKS_PER_SEC / sysconf(_SC_CLK_TCK));
+  timespec ts;
+  if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) == -1) {
+    return -1;
+  }
+  return (ts.tv_sec * CLOCKS_PER_SEC) + (ts.tv_nsec / (NS_PER_S / CLOCKS_PER_SEC));
 }
diff --git a/tests/time_test.cpp b/tests/time_test.cpp
index c631b6a..d2fec9a 100644
--- a/tests/time_test.cpp
+++ b/tests/time_test.cpp
@@ -404,3 +404,11 @@
   ASSERT_EQ(0, ts2.tv_sec);
   ASSERT_LT(ts2.tv_nsec, 1000000);
 }
+
+TEST(time, clock) {
+   // clock(3) is hard to test, but a 1s sleep should cost less than 1ms.
+   clock_t t0 = clock();
+   sleep(1);
+   clock_t t1 = clock();
+   ASSERT_LT(t1 - t0, CLOCKS_PER_SEC / 1000);
+}