diff --git a/scrapy/utils/project.py b/scrapy/utils/project.py
index a64fcda4f..a2edb7b08 100644
--- a/scrapy/utils/project.py
+++ b/scrapy/utils/project.py
@@ -51,10 +51,10 @@ def get_project_settings():
     if ENVVAR not in os.environ:
         project = os.environ.get('SCRAPY_PROJECT', 'default')
         init_env(project)
-    settings_module_path = os.environ.get(ENVVAR, 'scrapy_settings')
-    try:
+    settings_module_path = os.environ.get(ENVVAR)
+    if settings_module_path:
         settings_module = __import__(settings_module_path, {}, {}, [''])
-    except ImportError:
+    else:
         settings_module = None
     settings = CrawlerSettings(settings_module)
 
diff --git a/scrapy/utils/testproc.py b/scrapy/utils/testproc.py
index 22239d82f..cba3b4346 100644
--- a/scrapy/utils/testproc.py
+++ b/scrapy/utils/testproc.py
@@ -9,9 +9,10 @@ class ProcessTest(object):
     prefix = [sys.executable, '-m', 'scrapy.cmdline']
     cwd = os.getcwd() # trial chdirs to temp dir
 
-    def execute(self, args, check_code=True, settings='missing'):
+    def execute(self, args, check_code=True, settings=None):
         env = os.environ.copy()
-        env['SCRAPY_SETTINGS_MODULE'] = settings
+        if settings is not None:
+            env['SCRAPY_SETTINGS_MODULE'] = settings
         cmd = self.prefix + [self.command] + list(args)
         pp = TestProcessProtocol()
         pp.deferred.addBoth(self._process_finished, cmd, check_code)