diff --git a/testsuite/driver/perf_notes.py b/testsuite/driver/perf_notes.py
index 931af03751ec569eb88ab0094be42f481291da42..5c36bc2251ec13667ef669029022f1ccd91276f0 100644
--- a/testsuite/driver/perf_notes.py
+++ b/testsuite/driver/perf_notes.py
@@ -9,6 +9,7 @@
 # (which defaults to 'local' if not given by --test-env).
 #
 
+from enum import Enum
 import colorsys
 import tempfile
 import json
@@ -62,7 +63,7 @@ PerfStat = namedtuple('PerfStat', ['test_env','test','way','metric','value'])
 # A baseline recovered form stored metrics.
 Baseline = namedtuple('Baseline', ['perfStat','commit','commitDepth'])
 
-class MetricChange:
+class MetricChange(Enum):
     NewMetric = 'NewMetric'
     NoChange = 'NoChange'
     Increase = 'Increase'
diff --git a/testsuite/driver/testglobals.py b/testsuite/driver/testglobals.py
index 3d273cb6472843d05f1939f64452efbc2d380d42..c89e225c721ed2235b4701b6aead5e17b230ac4e 100644
--- a/testsuite/driver/testglobals.py
+++ b/testsuite/driver/testglobals.py
@@ -225,20 +225,22 @@ class TestRun:
        self.n_expected_failures = 0
 
        self.missing_libs = [] # type: List[TestResult]
-       self.framework_failures = []
-       self.framework_warnings = []
+       self.framework_failures = [] # type: List[TestResult]
+       self.framework_warnings = [] # type: List[TestResult]
 
-       self.expected_passes = []
-       self.unexpected_passes = []
-       self.unexpected_failures = []
-       self.unexpected_stat_failures = []
-       self.fragile_results = []
+       self.expected_passes = [] # type: List[TestResult]
+       self.unexpected_passes = [] # type: List[TestResult]
+       self.unexpected_failures = [] # type: List[TestResult]
+       self.unexpected_stat_failures = [] # type: List[TestResult]
+
+       # Results from tests that have been marked as fragile
+       self.fragile_results = [] # type: List[TestResult]
 
        # List of all metrics measured in this test run.
        # [(change, PerfStat)] where change is one of the  MetricChange
        # constants: NewMetric, NoChange, Increase, Decrease.
        # NewMetric happens when the previous git commit has no metric recorded.
-       self.metrics = []
+       self.metrics = [] # type: List[Tuple[MetricChange, PerfStat]]
 
 global t
 t = TestRun()