diff --git a/CHANGELOG.md b/CHANGELOG.md
index db0f5cd9..23b81923 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,15 +5,22 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Fix handling of debug flag when gunicorn is not present ([#44])
 
 ## [1.4.1] - 2020-05-07
+### Fixed
 - Fix Windows support ([#38])
 
 ## [1.4.0] - 2020-05-06
+### Changed
 - Use gunicorn as a production HTTP server
 
 ## [1.3.0] - 2020-04-13
+### Added
 - Add support for running `python -m functions_framework` ([#31])
+
+### Changed
 - Move `functions_framework.cli.cli` to `functions_framework._cli._cli`
 - Adjust path handling for robots.txt and favicon.ico ([#33])
 
@@ -56,6 +63,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [1.0.1]: https://github.com/GoogleCloudPlatform/functions-framework-python/releases/tag/v1.0.1
 [1.0.0]: https://github.com/GoogleCloudPlatform/functions-framework-python/releases/tag/v1.0.0
 
+[#44]: https://github.com/GoogleCloudPlatform/functions-framework-python/pull/44
 [#38]: https://github.com/GoogleCloudPlatform/functions-framework-python/pull/38
 [#33]: https://github.com/GoogleCloudPlatform/functions-framework-python/pull/33
 [#31]: https://github.com/GoogleCloudPlatform/functions-framework-python/pull/31
diff --git a/src/functions_framework/_http/__init__.py b/src/functions_framework/_http/__init__.py
index 0e532780..ca9b0f5c 100644
--- a/src/functions_framework/_http/__init__.py
+++ b/src/functions_framework/_http/__init__.py
@@ -18,9 +18,10 @@
 class HTTPServer:
     def __init__(self, app, debug, **options):
         self.app = app
+        self.debug = debug
         self.options = options
 
-        if debug:
+        if self.debug:
             self.server_class = FlaskApplication
         else:
             try:
@@ -31,7 +32,9 @@ def __init__(self, app, debug, **options):
                 self.server_class = FlaskApplication
 
     def run(self, host, port):
-        http_server = self.server_class(self.app, host, port, **self.options)
+        http_server = self.server_class(
+            self.app, host, port, self.debug, **self.options
+        )
         http_server.run()
 
 
diff --git a/src/functions_framework/_http/flask.py b/src/functions_framework/_http/flask.py
index 270390e7..b2edf563 100644
--- a/src/functions_framework/_http/flask.py
+++ b/src/functions_framework/_http/flask.py
@@ -14,11 +14,12 @@
 
 
 class FlaskApplication:
-    def __init__(self, app, host, port, **options):
+    def __init__(self, app, host, port, debug, **options):
         self.app = app
         self.host = host
         self.port = port
+        self.debug = debug
         self.options = options
 
     def run(self):
-        self.app.run(self.host, self.port, debug=True, **self.options)
+        self.app.run(self.host, self.port, debug=self.debug, **self.options)
diff --git a/src/functions_framework/_http/gunicorn.py b/src/functions_framework/_http/gunicorn.py
index fd0b0a3a..163b5317 100644
--- a/src/functions_framework/_http/gunicorn.py
+++ b/src/functions_framework/_http/gunicorn.py
@@ -16,7 +16,7 @@
 
 
 class GunicornApplication(gunicorn.app.base.BaseApplication):
-    def __init__(self, app, host, port, **options):
+    def __init__(self, app, host, port, debug, **options):
         self.options = {
             "bind": "%s:%s" % (host, port),
             "workers": 1,
diff --git a/tests/test_http.py b/tests/test_http.py
index 37fbf2cf..e9929d94 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -75,12 +75,15 @@ def test_httpserver(monkeypatch, debug, gunicorn_missing, expected):
 
     wrapper.run(host, port)
 
-    assert wrapper.server_class.calls == [pretend.call(app, host, port, **options)]
+    assert wrapper.server_class.calls == [
+        pretend.call(app, host, port, debug, **options)
+    ]
     assert http_server.run.calls == [pretend.call()]
 
 
 @pytest.mark.skipif("platform.system() == 'Windows'")
-def test_gunicorn_application():
+@pytest.mark.parametrize("debug", [True, False])
+def test_gunicorn_application(debug):
     app = pretend.stub()
     host = "1.2.3.4"
     port = "1234"
@@ -89,7 +92,7 @@ def test_gunicorn_application():
     import functions_framework._http.gunicorn
 
     gunicorn_app = functions_framework._http.gunicorn.GunicornApplication(
-        app, host, port, **options
+        app, host, port, debug, **options
     )
 
     assert gunicorn_app.app == app
@@ -107,23 +110,25 @@ def test_gunicorn_application():
     assert gunicorn_app.load() == app
 
 
-def test_flask_application():
+@pytest.mark.parametrize("debug", [True, False])
+def test_flask_application(debug):
     app = pretend.stub(run=pretend.call_recorder(lambda *a, **kw: None))
     host = pretend.stub()
     port = pretend.stub()
     options = {"a": pretend.stub(), "b": pretend.stub()}
 
     flask_app = functions_framework._http.flask.FlaskApplication(
-        app, host, port, **options
+        app, host, port, debug, **options
     )
 
     assert flask_app.app == app
     assert flask_app.host == host
     assert flask_app.port == port
+    assert flask_app.debug == debug
     assert flask_app.options == options
 
     flask_app.run()
 
     assert app.run.calls == [
-        pretend.call(host, port, debug=True, a=options["a"], b=options["b"]),
+        pretend.call(host, port, debug=debug, a=options["a"], b=options["b"]),
     ]