diff --git a/octoprint_octolapse/camera.py b/octoprint_octolapse/camera.py
index b8791726..9a4cfe04 100644
--- a/octoprint_octolapse/camera.py
+++ b/octoprint_octolapse/camera.py
@@ -578,7 +578,7 @@ def _test_web_camera(camera_profile, timeout_seconds=2, is_before_print_test=Fal
                     message = "The request contained no data for the '{0}' camera profile.".format(camera_profile.name)
                     logger.error(message)
                     raise CameraError('request-contained-no-data', message)
-                elif "image/jpeg" not in r.headers["content-type"].lower():
+                elif 'content-type' in r.headers and "image/jpeg" not in r.headers["content-type"].lower():
                     message = (
                         "The returned data was not an image for the '{0}' camera profile.".format(camera_profile.name)
                     )