diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 4768945a212..0436c2e99da 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -2934,10 +2934,6 @@ void nsGfxScrollFrameInner::CurPosAttributeChanged(nsIContent* aContent)
                (mVScrollbarBox && mVScrollbarBox->GetContent() == aContent),
                "unexpected child");
 
-  if (mScrollbarActivity) {
-    mScrollbarActivity->ActivityOccurred();
-  }
-
   // Attribute changes on the scrollbars happen in one of three ways:
   // 1) The scrollbar changed the attribute in response to some user event
   // 2) We changed the attribute in response to a ScrollPositionDidChange
@@ -2970,6 +2966,10 @@ void nsGfxScrollFrameInner::CurPosAttributeChanged(nsIContent* aContent)
     return;
   }
 
+  if (mScrollbarActivity) {
+    mScrollbarActivity->ActivityOccurred();
+  }
+
   bool isSmooth = aContent->HasAttr(kNameSpaceID_None, nsGkAtoms::smooth);
   if (isSmooth) {
     // Make sure an attribute-setting callback occurs even if the view