diff --git a/src/include/portability/instr_time.h b/src/include/portability/instr_time.h
index a6fc1922f2..5509d23d2f 100644
--- a/src/include/portability/instr_time.h
+++ b/src/include/portability/instr_time.h
@@ -84,7 +84,7 @@ typedef struct instr_time
 
 /* Use clock_gettime() */
 
-#include <time.h>
+#include <sys/time.h>
 
 /*
  * The best clockid to use according to the POSIX spec is CLOCK_MONOTONIC,
@@ -111,10 +111,10 @@ static inline instr_time
 pg_clock_gettime_ns(void)
 {
 	instr_time	now;
-	struct timespec tmp;
+	struct timeval tmp;
 
-	clock_gettime(PG_INSTR_CLOCK, &tmp);
-	now.ticks = tmp.tv_sec * NS_PER_S + tmp.tv_nsec;
+	gettimeofday(&tmp, NULL);
+	now.ticks = tmp.tv_sec * NS_PER_S + tmp.tv_usec * 1000;
 
 	return now;
 }