diff --git a/authfs/tests/benchmarks/src/measure_io.cpp b/authfs/tests/benchmarks/src/measure_io.cpp
index e1f2fb8..e766664 100644
--- a/authfs/tests/benchmarks/src/measure_io.cpp
+++ b/authfs/tests/benchmarks/src/measure_io.cpp
@@ -55,7 +55,10 @@
     }
 
     char buf[kBlockSizeBytes];
-    clock_t start = clock();
+    struct timespec start;
+    if (clock_gettime(CLOCK_MONOTONIC, &start) == -1) {
+        err(EXIT_FAILURE, "failed to clock_gettime");
+    }
     for (auto i = 0; i < block_count; ++i) {
         auto bytes = is_read ? pread(fd, buf, kBlockSizeBytes, offsets[i])
                              : pwrite(fd, buf, kBlockSizeBytes, offsets[i]);
@@ -69,7 +72,11 @@
         // Writes all the buffered modifications to the open file.
         assert(syncfs(fd) == 0);
     }
-    double elapsed_seconds = ((double)clock() - start) / CLOCKS_PER_SEC;
+    struct timespec finish;
+    if (clock_gettime(CLOCK_MONOTONIC, &finish) == -1) {
+        err(EXIT_FAILURE, "failed to clock_gettime");
+    }
+    double elapsed_seconds = finish.tv_sec - start.tv_sec + (finish.tv_nsec - start.tv_nsec) / 1e9;
     double rate = (double)file_size_mb / elapsed_seconds;
     std::cout << std::setprecision(12) << rate << std::endl;
 
diff --git a/tests/benchmark/src/jni/io_vsock_host_jni.cpp b/tests/benchmark/src/jni/io_vsock_host_jni.cpp
index dd32e29..47d5325 100644
--- a/tests/benchmark/src/jni/io_vsock_host_jni.cpp
+++ b/tests/benchmark/src/jni/io_vsock_host_jni.cpp
@@ -20,6 +20,7 @@
 #include <jni.h>
 #include <time.h>
 
+using android::base::ErrnoError;
 using android::base::Error;
 using android::base::Result;
 using android::base::WriteStringToFd;
@@ -29,12 +30,18 @@
 Result<double> measure_send_rate(int fd, int num_bytes_to_send) {
     std::string data;
     data.assign(num_bytes_to_send, 'a');
-    clock_t start = clock();
+    struct timespec start;
+    if (clock_gettime(CLOCK_MONOTONIC, &start) == -1) {
+        return ErrnoError() << "failed to clock_gettime";
+    }
     if (!WriteStringToFd(data, fd)) {
         return Error() << "Cannot send data to client";
     }
-    clock_t end = clock();
-    double elapsed_seconds = (double)(end - start) / CLOCKS_PER_SEC;
+    struct timespec finish;
+    if (clock_gettime(CLOCK_MONOTONIC, &finish) == -1) {
+        return ErrnoError() << "failed to clock_gettime";
+    }
+    double elapsed_seconds = finish.tv_sec - start.tv_sec + (finish.tv_nsec - start.tv_nsec) / 1e9;
     LOG(INFO) << "Host:Finished sending data in " << elapsed_seconds << " seconds.";
     double send_rate = (double)num_bytes_to_send / kNumBytesPerMB / elapsed_seconds;
     return {send_rate};
diff --git a/tests/benchmark/src/native/benchmarkbinary.cpp b/tests/benchmark/src/native/benchmarkbinary.cpp
index 56963e6..6cfc71d 100644
--- a/tests/benchmark/src/native/benchmarkbinary.cpp
+++ b/tests/benchmark/src/native/benchmarkbinary.cpp
@@ -118,7 +118,10 @@
         }
         char buf[kBlockSizeBytes];
 
-        clock_t start = clock();
+        struct timespec start;
+        if (clock_gettime(CLOCK_MONOTONIC, &start) == -1) {
+            return ErrnoError() << "failed to clock_gettime";
+        }
         unique_fd fd(open(filename.c_str(), O_RDONLY | O_CLOEXEC));
         if (fd.get() == -1) {
             return ErrnoError() << "Read: opening " << filename << " failed";
@@ -131,7 +134,12 @@
                 return ErrnoError() << "failed to read";
             }
         }
-        double elapsed_seconds = ((double)clock() - start) / CLOCKS_PER_SEC;
+        struct timespec finish;
+        if (clock_gettime(CLOCK_MONOTONIC, &finish) == -1) {
+            return ErrnoError() << "failed to clock_gettime";
+        }
+        double elapsed_seconds =
+                finish.tv_sec - start.tv_sec + (finish.tv_nsec - start.tv_nsec) / 1e9;
         double file_size_mb = (double)file_size_bytes / kNumBytesPerMB;
         return {file_size_mb / elapsed_seconds};
     }