diff --git a/tests/src/mmap_stress.c b/tests/src/mmap_stress.c
index 94a41484..c541bd6b 100644
--- a/tests/src/mmap_stress.c
+++ b/tests/src/mmap_stress.c
@@ -19,6 +19,7 @@
 #include <sys/types.h>
 #include <stdio.h>
 #include <sys/stat.h>
+#include <inttypes.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdlib.h>
@@ -29,7 +30,7 @@
 #include <errno.h>
 
 static int size = 0;
-static int count = 0; /* XXX make this duration instead */
+static int duration = 0;
 
 struct thread_info {
 	int nr;
@@ -41,6 +42,8 @@ static void *run_test_func(void *ptr)
 	void *buf = NULL;
 	char *addr = NULL;
 	struct thread_info *tinfo = ptr;
+	uint64_t seconds = 0;
+	struct timespec ts;
 	int c = 0;
 	int fd;
 	ssize_t read, written, ret;
@@ -61,9 +64,15 @@ static void *run_test_func(void *ptr)
 
 	usleep(100000); /* 0.1sec to allow all threads to start roughly at the same time */
 
+	clock_gettime(CLOCK_REALTIME, &ts); /* record start time */
+	seconds = ts.tv_sec + duration;
+
 	for (;;) {
-		if (++c > count)
-			break;
+		if (++c % 16 == 0) {
+			clock_gettime(CLOCK_REALTIME, &ts);
+			if (ts.tv_sec >= seconds)
+				break;
+		}
 
 		switch (rand() % 4) {
 		case 0: /* pread */
@@ -120,7 +129,7 @@ int main(int argc, char **argv)
 	int i;
 
 	if (argc != 8) {
-		fprintf(stderr, "%s requires 7 arguments - size count file1 file2 file3 file4 file5\n", argv[0]);
+		fprintf(stderr, "%s requires 7 arguments - size duration file1 file2 file3 file4 file5\n", argv[0]);
 		exit(-1);
 	}
 
@@ -130,9 +139,9 @@ int main(int argc, char **argv)
 		exit(-1);
 	}
 
-	count = atoi(argv[2]);
-	if (count < 0) {
-		fprintf(stderr, "invalid count, must be greater than 0\n");
+	duration = atoi(argv[2]);
+	if (duration < 0) {
+		fprintf(stderr, "invalid duration, must be greater than or equal to 0\n");
 		exit(-1);
 	}
 
diff --git a/tests/tests/mmap.sh b/tests/tests/mmap.sh
index bf465ce9..4b14d516 100644
--- a/tests/tests/mmap.sh
+++ b/tests/tests/mmap.sh
@@ -5,7 +5,7 @@
 t_require_commands mmap_stress mmap_validate scoutfs xfs_io
 
 echo "== mmap_stress"
-mmap_stress 8192 2000 "$T_D0/mmap_stress" "$T_D1/mmap_stress" "$T_D2/mmap_stress" "$T_D3/mmap_stress" "$T_D4/mmap_stress" | sed 's/:.*//g' | sort
+mmap_stress 8192 30 "$T_D0/mmap_stress" "$T_D1/mmap_stress" "$T_D2/mmap_stress" "$T_D3/mmap_stress" "$T_D4/mmap_stress" | sed 's/:.*//g' | sort
 
 echo "== basic mmap/read/write consistency checks"
 mmap_validate 256 1000 "$T_D0/mmap_val1" "$T_D1/mmap_val1"