diff --git a/common/content/options.js b/common/content/options.js
index f3f415bf..45525735 100644
--- a/common/content/options.js
+++ b/common/content/options.js
@@ -1144,7 +1144,7 @@ const Options = Module("options", {
                     context.completions = [
                             [option.value, "Current value"],
                             [option.defaultValue, "Default value"]
-                    ].filter(function (f) f[0] != "" && f[0].length < 200);
+                    ].filter(function (f) f[0] !== "" && String(f[0]).length < 200);
                 });
             }