--- a/mozilla-tests/b2g_config.py
+++ b/mozilla-tests/b2g_config.py
@@ -2627,17 +2627,17 @@ for branch in BRANCHES.keys():
 BRANCHES['alder']['branch_name'] = "Alder"
 BRANCHES['alder']['repo_path'] = "projects/alder"
 BRANCHES['ash']['branch_name'] = "Ash"
 BRANCHES['ash']['repo_path'] = "projects/ash"
 BRANCHES['cedar']['branch_name'] = "Cedar"
 BRANCHES['cedar']['repo_path'] = "projects/cedar"
 BRANCHES['cedar']['mozharness_tag'] = "default"
 BRANCHES['cedar']['platforms']['emulator']['ubuntu64_vm-b2g-emulator']['opt_unittest_suites'] = \
-    MOCHITEST + REFTEST_20 + CRASHTEST + XPCSHELL + MARIONETTE + MARIONETTE_UNIT + JSREFTEST + CPPUNIT + MOCHITEST_CHROME
+    MOCHITEST + REFTEST_20 + CRASHTEST + XPCSHELL + MARIONETTE + MARIONETTE_UNIT + JSREFTEST + CPPUNIT
 BRANCHES['cedar']['platforms']['emulator']['ubuntu64_vm-b2g-emulator']['debug_unittest_suites'] = \
     MOCHITEST_EMULATOR_DEBUG[:] + REFTEST + CRASHTEST + MARIONETTE + MARIONETTE_UNIT + XPCSHELL_CHUNKED + CPPUNIT
 BRANCHES['cedar']['platforms']['emulator']['ubuntu64_vm-b2g-lg-emulator']['opt_unittest_suites'] = MOCHITEST_MEDIA
 BRANCHES['cedar']['platforms']['emulator-jb']['ubuntu64_vm-b2g-emulator-jb']['opt_unittest_suites'] = MOCHITEST_EMULATOR_JB[:]
 BRANCHES['cedar']['platforms']['emulator-kk']['ubuntu64_vm-b2g-emulator-kk']['opt_unittest_suites'] = \
     MOCHITEST + REFTEST_20 + CRASHTEST + XPCSHELL + MARIONETTE + MARIONETTE_UNIT + JSREFTEST + CPPUNIT + MOCHITEST_CHROME
 BRANCHES['cedar']['platforms']['emulator-kk']['ubuntu64_vm-b2g-emulator-kk']['debug_unittest_suites'] = \
     MOCHITEST_EMULATOR_DEBUG[:] + REFTEST + CRASHTEST + MARIONETTE + MARIONETTE_UNIT + XPCSHELL_CHUNKED + CPPUNIT
@@ -2704,16 +2704,22 @@ for name, branch in items_at_least(BRANC
             if s[0] == suite_to_remove:
                 BRANCHES[name]['platforms']['linux64_gecko']['ubuntu64_vm-b2gdt']['opt_unittest_suites'].remove(s)
 
 # new linux64_gecko tests as of gecko 34
 for name, branch in items_at_least(BRANCHES, 'gecko_version', 34):
     BRANCHES[name]['platforms']['linux64_gecko']['ubuntu64_vm-b2gdt']['opt_unittest_suites'] += \
       GAIA_BUILD_UNIT
 
+# add mochitest-chrome on B2G emulators as of gecko 38
+for name, branch in items_at_least(BRANCHES, 'gecko_version', 38):
+    if nested_haskey(BRANCHES[name]['platforms'], 'emulator', 'ubuntu64_vm-b2g-emulator'):
+        BRANCHES[name]['platforms']['emulator']['ubuntu64_vm-b2g-emulator']['opt_unittest_suites'] += \
+            MOCHITEST_CHROME
+
 # Use chunked Gip, Gij in 36+ (bug 1081246)
 for name, branch in items_at_least(BRANCHES, 'gecko_version', 36):
     for slave_platform in (('linux64_gecko', 'ubuntu64_vm-b2gdt'),
                            ('macosx64_gecko', 'mountainlion-b2gdt')):
         if slave_platform[0] in BRANCHES[name]['platforms']:
             BRANCHES[name]['platforms'][slave_platform[0]][slave_platform[1]]['opt_unittest_suites'] += GIP[:]
             if slave_platform[0] == 'linux64_gecko':
                 BRANCHES[name]['platforms'][slave_platform[0]][slave_platform[1]]['debug_unittest_suites'] += GIP[:]