diff --git a/src/modules/displaymanager/main.py b/src/modules/displaymanager/main.py
index c64642f23..1c8eb2bf4 100644
--- a/src/modules/displaymanager/main.py
+++ b/src/modules/displaymanager/main.py
@@ -469,11 +469,13 @@ def run():
 
                 if (os.path.exists(greeter_desktop)):
                     libcalamares.utils.debug("configure {!s}".format(greeter))
-                    "sed -i -e "
-                    "\"s/^.*greeter-session=.*/greeter-session={!s}/\" "
-                    "{!s}".format(
-                        greeter,
-                        lightdm_conf_path
+                    os.system(
+                        "sed -i -e "
+                        "\"s/^.*greeter-session=.*/greeter-session={!s}/\" "
+                        "{!s}".format(
+                            greeter,
+                            lightdm_conf_path
+                            )
                         )
                 else:
                     return ("No lightdm greeter installed.")