diff --git a/tests/test_browser.py b/tests/test_browser.py
index 593794241966a..610b8572ebe98 100644
--- a/tests/test_browser.py
+++ b/tests/test_browser.py
@@ -3783,7 +3783,6 @@ def test_pthread_main_thread_blocking(self, name):
       self.btest_exit(test_file('pthread/main_thread_%s.cpp' % name), args=['-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE', '-s', 'PROXY_TO_PTHREAD', '-s', 'ALLOW_BLOCKING_ON_MAIN_THREAD=0'])
 
   # Test the old GCC atomic __sync_fetch_and_op builtin operations.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_gcc_atomic_fetch_and_op(self):
     for opt in [[], ['-O1'], ['-O2'], ['-O3'], ['-Os']]:
@@ -3793,25 +3792,21 @@ def test_pthread_gcc_atomic_fetch_and_op(self):
         self.btest_exit(test_file('pthread/test_pthread_gcc_atomic_fetch_and_op.cpp'), args=args + ['-s', 'INITIAL_MEMORY=64MB', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'])
 
   # 64 bit version of the above test.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_gcc_64bit_atomic_fetch_and_op(self):
     self.btest_exit(test_file('pthread/test_pthread_gcc_64bit_atomic_fetch_and_op.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'], also_asmjs=True)
 
   # Test the old GCC atomic __sync_op_and_fetch builtin operations.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_gcc_atomic_op_and_fetch(self):
     self.btest_exit(test_file('pthread/test_pthread_gcc_atomic_op_and_fetch.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'], also_asmjs=True)
 
   # 64 bit version of the above test.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_gcc_64bit_atomic_op_and_fetch(self):
     self.btest_exit(test_file('pthread/test_pthread_gcc_64bit_atomic_op_and_fetch.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'], also_asmjs=True)
 
   # Tests the rest of the remaining GCC atomics after the two above tests.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_gcc_atomics(self):
     self.btest_exit(test_file('pthread/test_pthread_gcc_atomics.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'])
@@ -3823,7 +3818,6 @@ def test_pthread_gcc_spinlock(self):
       self.btest_exit(test_file('pthread/test_pthread_gcc_spinlock.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'] + arg, also_asmjs=True)
 
   # Test that basic thread creation works.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_create(self):
     def test(args):
@@ -3926,7 +3920,6 @@ def test_pthread_once(self):
     self.btest_exit(test_file('pthread/test_pthread_once.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8'])
 
   # Test against a certain thread exit time handling bug by spawning tons of threads.
-  @no_firefox('https://bugzilla.mozilla.org/show_bug.cgi?id=1666568')
   @requires_threads
   def test_pthread_spawns(self):
     self.btest_exit(test_file('pthread/test_pthread_spawns.cpp'), args=['-s', 'INITIAL_MEMORY=64MB', '-O3', '-s', 'USE_PTHREADS', '-s', 'PTHREAD_POOL_SIZE=8', '--closure=1', '-s', 'ENVIRONMENT=web,worker'])