diff --git a/common/content/completion.js b/common/content/completion.js
index 9ba3d7c1..3334055d 100644
--- a/common/content/completion.js
+++ b/common/content/completion.js
@@ -335,7 +335,7 @@ const CompletionContext = Class("CompletionContext", {
             this.lastActivated = this.top.runCount;
         }
         if (!this.itemCache[this.key]) {
-            let res = this._generate.call(this) || [];
+            let res = this._generate.call(this);
             if (res != null)
                 this.itemCache[this.key] = res;
         }
@@ -356,7 +356,8 @@ const CompletionContext = Class("CompletionContext", {
                 if (this.cache.backgroundLock != lock)
                     return;
                 this.incomplete = false;
-                this.completions = items;
+                if (items != null)
+                    this.completions = items;
             });
         }
     },
diff --git a/common/content/dactyl.js b/common/content/dactyl.js
index d79ec818..2c042952 100644
--- a/common/content/dactyl.js
+++ b/common/content/dactyl.js
@@ -1459,7 +1459,7 @@ const Dactyl = Module("dactyl", {
                         services.get("extensionManager").uninstallItem(this.id);
                     };
                     addon.appDisabled = false;
-                    addon.__defineGetter__("userDisabled", function () getRdfProperty("userDisabled") == "true");
+                    addon.__defineGetter__("userDisabled", function () getRdfProperty(addon, "userDisabled") == "true");
                     addon.__defineSetter__("userDisabled", function (val) {
                         services.get("extensionManager")[val ? "enableItem" : "disableItem"](this.id);
                     });