--- a/mozilla-tests/config.py
+++ b/mozilla-tests/config.py
@@ -467,24 +467,24 @@ MOCHITEST_DT_E10S = [
         'use_mozharness': True,
         'script_path': 'scripts/desktop_unittest.py',
         'extra_args': ['--mochitest-suite', 'mochitest-devtools-chrome', '--e10s'],
         'blob_upload': True,
         'script_maxtime': 7200,
     }),
 ]
 
-MOCHITEST_DT_3 = [
+MOCHITEST_DT_4 = [
     ('mochitest-devtools-chrome', {
         'use_mozharness': True,
         'script_path': 'scripts/desktop_unittest.py',
         'extra_args': ['--mochitest-suite', 'mochitest-devtools-chrome-chunked'],
         'blob_upload': True,
         'script_maxtime': 4800,
-        'totalChunks': 3,
+        'totalChunks': 4,
     }),
 ]
 
 MOCHITEST_BC_3 = [
     ('mochitest-browser-chrome', {
         'use_mozharness': True,
         'script_path': 'scripts/desktop_unittest.py',
         'extra_args': ['--mochitest-suite', 'browser-chrome-chunked'],
@@ -710,17 +710,17 @@ WEB_PLATFORM_TESTS_CHUNKED = [
         'blob_upload': True,
         'script_maxtime': 7200,
     }),
 ]
 
 
 UNITTEST_SUITES = {
     'opt_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MOCHITEST_DT,
-    'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MARIONETTE + MOCHITEST_DT_3,
+    'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MARIONETTE + MOCHITEST_DT_4,
 }
 
 
 # You must define opt_unittest_suites when enable_opt_unittests is True for a
 # platform. Likewise debug_unittest_suites for enable_debug_unittests
 PLATFORM_UNITTEST_VARS = {
     'linux': {
         'product_name': 'firefox',
@@ -1071,17 +1071,17 @@ PLATFORM_UNITTEST_VARS = {
         'builds_before_reboot': 1,
         'mochitest_leak_threshold': 484,
         'crashtest_leak_threshold': 484,
         'env_name': 'win32-perf-unittest',
         'enable_opt_unittests': True,
         'enable_debug_unittests': True,
         'xp-ix': {
             'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:],
-            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + MOCHITEST_DT_3,
+            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + MOCHITEST_DT_4,
             'suite_config': {
                 'mochitest': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-e10s': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-csb': {
@@ -1149,17 +1149,17 @@ PLATFORM_UNITTEST_VARS = {
                 },
                 'web-platform-tests-reftests': {
                     'config_files': ["web_platform_tests/prod_config_windows.py"],
                 },
             },
         },
         'win7-ix': {
             'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:] + REFTEST_NOACCEL,
-            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + MOCHITEST_DT_3,
+            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + MOCHITEST_DT_4,
             'suite_config': {
                 'mochitest': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-e10s': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-csb': {
@@ -1230,17 +1230,17 @@ PLATFORM_UNITTEST_VARS = {
                 },
                 'web-platform-tests-reftests': {
                     'config_files': ["web_platform_tests/prod_config_windows.py"],
                 },
             },
         },
         'win8': {
             'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:] + REFTEST_NOACCEL[:],
-            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MOCHITEST_DT_3,
+            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MOCHITEST_DT_4,
             'suite_config': {
                 'mochitest': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-e10s': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-csb': {
@@ -1322,17 +1322,17 @@ PLATFORM_UNITTEST_VARS = {
         'builds_before_reboot': 1,
         'mochitest_leak_threshold': 484,
         'crashtest_leak_threshold': 484,
         'env_name': 'win64-perf-unittest',
         'enable_opt_unittests': True,
         'enable_debug_unittests': True,
         'win8_64': {
             'opt_unittest_suites': UNITTEST_SUITES['opt_unittest_suites'][:] + REFTEST_NOACCEL[:],
-            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MOCHITEST_DT_3,
+            'debug_unittest_suites': MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + XPCSHELL + CPPUNIT + MOCHITEST_DT_4,
             'suite_config': {
                 'mochitest': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-e10s': {
                     'config_files': ["unittests/win_unittest.py"],
                 },
                 'mochitest-csb': {
@@ -1919,17 +1919,17 @@ BRANCHES['mozilla-b2g30_v1_4']['script_r
 # Filter the tests that are enabled on holly for bug 985718.
 for platform in BRANCHES['holly']['platforms'].keys():
     if platform not in PLATFORMS:
         continue
 
     for slave_platform in PLATFORMS[platform]['slave_platforms']:
         slave_p = BRANCHES['holly']['platforms'][platform][slave_platform]
         slave_p['opt_unittest_suites'] = MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + MOCHITEST_DT
-        slave_p['debug_unittest_suites'] = MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + MOCHITEST_DT_3
+        slave_p['debug_unittest_suites'] = MOCHITEST + REFTEST_ONE_CHUNK + REFTEST_NO_IPC + MOCHITEST_DT_4
 
         # Enable content sandbox tests for Windows bit
         if slave_platform in PLATFORMS['win64']['slave_platforms'] or slave_platform in PLATFORMS['win32']['slave_platforms']:
             slave_p['opt_unittest_suites'] += MOCHITEST_CSB
             slave_p['debug_unittest_suites'] += MOCHITEST_CSB
 
 # Enable Yosemite testing on select branches only
 delete_slave_platform(BRANCHES, PLATFORMS, {'macosx64': 'yosemite'}, branch_exclusions=['try'])
@@ -2265,17 +2265,17 @@ for name, branch in items_before(BRANCHE
             if slave_platform in ('mountainlion', ) and 'b2g' in name:
                 del branch['platforms'][platform][slave_platform]
                 continue
             try:
                 branch['platforms'][platform][slave_platform]['opt_unittest_suites'].remove(MOCHITEST_DT[0])
             except ValueError:
                 # wasn't there anyways
                 pass
-            for dt in MOCHITEST_DT_3:
+            for dt in MOCHITEST_DT_4:
                 try:
                     branch['platforms'][platform][slave_platform]['debug_unittest_suites'].remove(dt)
                 except ValueError:
                     # wasn't there anyways
                     pass
 
 # Disable Linux64-cc in every branch except try
 for name in BRANCHES.keys():