diff --git a/modules/audio_coding/codecs/isac/fix/test/kenny.cc b/modules/audio_coding/codecs/isac/fix/test/kenny.cc
index 4b431cfdf9..a0a2dca118 100644
--- a/modules/audio_coding/codecs/isac/fix/test/kenny.cc
+++ b/modules/audio_coding/codecs/isac/fix/test/kenny.cc
@@ -105,7 +105,7 @@ TEST(IsacFixTest, Kenny) {
   FILE *inp, *outp, *f_bn, *outbits;
   int endfile;
 
-  const char* perf_result_file = NULL;
+  const char* chartjson_result_file = NULL;
 
   int i;
   int errtype, h = 0, k, packetLossPercent = 0;
@@ -459,7 +459,7 @@ TEST(IsacFixTest, Kenny) {
         printf("Expected --isolated_script_test_perf_output=/some/filename\n");
         exit(1);
       }
-      perf_result_file = filename_start + 1;
+      chartjson_result_file = filename_start + 1;
     }
   }
 
@@ -858,10 +858,10 @@ TEST(IsacFixTest, Kenny) {
 
   // Record the results with Perf test tools.
   webrtc::test::PrintResult("isac", "", "time_per_10ms_frame",
-                            (runtime * 10) / length_file, "ms", false);
+                            (runtime * 10000) / length_file, "us", false);
 
-  if (perf_result_file) {
-    EXPECT_TRUE(webrtc::test::WritePerfResults(perf_result_file));
+  if (chartjson_result_file) {
+    EXPECT_TRUE(webrtc::test::WritePerfResults(chartjson_result_file));
   }
 
   fclose(inp);
diff --git a/test/testsupport/perf_test.cc b/test/testsupport/perf_test.cc
index 5b2f7a0479..ff0f0d9b6b 100644
--- a/test/testsupport/perf_test.cc
+++ b/test/testsupport/perf_test.cc
@@ -24,7 +24,7 @@
 
 ABSL_FLAG(bool,
           write_histogram_proto_json,
-          true,
+          false,
           "Use the histogram C++ API, which will write Histogram protos "
           "instead of Chart JSON. See histogram.proto in third_party/catapult. "
           "This flag only has effect  if --isolated_script_test_perf_output is "
diff --git a/test/testsupport/perf_test_unittest.cc b/test/testsupport/perf_test_unittest.cc
index d99014bf80..1004c6495e 100644
--- a/test/testsupport/perf_test_unittest.cc
+++ b/test/testsupport/perf_test_unittest.cc
@@ -97,9 +97,6 @@ TEST_F(PerfTest, MAYBE_TestPrintResult) {
 }
 
 TEST_F(PerfTest, TestGetPerfResultsJSON) {
-  bool original_flag = absl::GetFlag(FLAGS_write_histogram_proto_json);
-  absl::SetFlag(&FLAGS_write_histogram_proto_json, false);
-
   PrintResult("measurement", "modifier", "trace", 42, "units", false);
   PrintResult("foo", "bar", "baz_v", 7, "widgets", true);
   PrintResultMeanAndError("foo", "bar", "baz_me", 1, 2, "lemurs", false);
@@ -107,19 +104,19 @@ TEST_F(PerfTest, TestGetPerfResultsJSON) {
   PrintResultList("foo", "bar", "baz_vl", kListOfScalars, "units", false);
 
   EXPECT_EQ(RemoveSpaces(kJsonExpected), GetPerfResults());
-
-  absl::SetFlag(&FLAGS_write_histogram_proto_json, original_flag);
 }
 
 TEST_F(PerfTest, TestClearPerfResults) {
   PrintResult("measurement", "modifier", "trace", 42, "units", false);
   ClearPerfResults();
-  EXPECT_EQ("", GetPerfResults());
+  EXPECT_EQ(R"({"format_version":"1.0","charts":{}})", GetPerfResults());
 }
 
 #if WEBRTC_ENABLE_PROTOBUF
 
 TEST_F(PerfTest, TestGetPerfResultsHistograms) {
+  bool original_flag = absl::GetFlag(FLAGS_write_histogram_proto_json);
+  absl::SetFlag(&FLAGS_write_histogram_proto_json, true);
   PrintResult("measurement", "_modifier", "story_1", 42, "ms", false);
   PrintResult("foo", "bar", "story_1", 7, "sigma", true);
   // Note: the error will be ignored, not supported by histograms.
@@ -156,6 +153,8 @@ TEST_F(PerfTest, TestGetPerfResultsHistograms) {
 
   EXPECT_EQ(hist2.name(), "measurement_modifier");
   EXPECT_EQ(hist2.unit().unit(), proto::MS_BEST_FIT_FORMAT);
+
+  absl::SetFlag(&FLAGS_write_histogram_proto_json, original_flag);
 }
 
 TEST_F(PerfTest, TestClearPerfResultsHistograms) {