--- a/mozilla-tests/config.py
+++ b/mozilla-tests/config.py
@@ -778,16 +778,27 @@ REFTEST_NOACCEL_TWO_CHUNKS = [
         'script_path': 'scripts/desktop_unittest.py',
         'extra_args': ['--reftest-suite', 'reftest-no-accel'],
         'blob_upload': True,
         'script_maxtime': 7200,
         'totalChunks': 2,
     }),
 ]
 
+REFTEST_NOACCEL_SIX_CHUNKS = [
+    ('reftest-no-accel', {
+        'use_mozharness': True,
+        'script_path': 'scripts/desktop_unittest.py',
+        'extra_args': ['--reftest-suite', 'reftest-no-accel'],
+        'blob_upload': True,
+        'script_maxtime': 7200,
+        'totalChunks': 6,
+    }),
+]
+
 REFTEST_NOACCEL_E10S_TWO_CHUNKS = [
     ('reftest-no-accel-e10s', {
         'use_mozharness': True,
         'script_path': 'scripts/desktop_unittest.py',
         'extra_args': ['--reftest-suite', 'reftest-no-accel', '--e10s'],
         'blob_upload': True,
         'script_maxtime': 7200,
         'totalChunks': 2,
@@ -3140,16 +3151,21 @@ for name, branch in items_at_least(BRANC
                         WEB_PLATFORM_TESTS_CHUNKED_E10S
             if platform in ['linux64-asan']:
                 branch['platforms'][platform][slave_platform]['opt_unittest_suites'] += \
                     MARIONETTE + MARIONETTE_E10S + MOCHITEST_DT_8_E10S + \
                     REFTEST_E10S_TWO_CHUNKS + REFTEST_NOACCEL_E10S_TWO_CHUNKS
             if platform in ('linux',):
                 branch['platforms'][platform][slave_platform]['debug_unittest_suites'] += \
                     REFTEST_NOACCEL_E10S_TWO_CHUNKS
+                # we want reftest_noaccel to be 6 chunks for debug on gecko version 48+
+                for test, config in branch['platforms'][platform][slave_platform]['debug_unittest_suites']:
+                    if test == 'reftest-no-accel':
+                        branch['platforms'][platform][slave_platform]['debug_unittest_suites'].remove((test,config))
+                        branch['platforms'][platform][slave_platform]['debug_unittest_suites'] += REFTEST_NOACCEL_SIX_CHUNKS
             if platform in ('linux','linux64'):
                 branch['platforms'][platform][slave_platform]['opt_unittest_suites'] += \
                     REFTEST_NOACCEL_E10S_TWO_CHUNKS
 
 # Bug 1277885 - Enable e10s tests for all Windows platforms on Try
 # Win7 already runs by default on production. WinXP, Win8, and Win10 are all opt-in platforms.
 for platform in PLATFORMS.keys():
     if platform not in BRANCHES['try']['platforms']: