diff -r 2c67b0fa6ff5 -r 73656aba2c89 UserPreferences.st
--- a/UserPreferences.st	Mon Jul 06 06:06:17 2015 +0100
+++ b/UserPreferences.st	Tue Jul 07 06:36:18 2015 +0200
@@ -4039,6 +4039,8 @@
     Smalltalk loadPackage:packageName.
 
     "
+     UserPreferences current preloadedPackages
+
      UserPreferences current addPreloadedPackage:'stx:goodies/smallsense'
      UserPreferences current removePreloadedPackage:'stx:goodies/smallsense'
     "
@@ -4080,9 +4082,16 @@
     "remove this from the set of preloaded packages.
      This will be no longer be automatically loaded whenever the system starts"
 
-    (self at:#preloadedPackages ifAbsentPut:[Set new]) remove:packageName ifAbsent:[]
-
-    "
+    |preloaded|
+
+    preloaded := self at:#preloadedPackages ifAbsent:[nil].
+    preloaded notNil ifTrue:[
+        preloaded remove:packageName ifAbsent:[]
+    ].
+
+    "
+     UserPreferences current preloadedPackages
+
      UserPreferences current addPreloadedPackage:'stx:goodies/smallsense'
      UserPreferences current removePreloadedPackage:'stx:goodies/smallsense'
     "