diff --git a/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js b/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
index e858738c62ed..7f820a93667c 100644
--- a/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
+++ b/gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js
@@ -250,8 +250,12 @@ function synthesizeNativeClick(aElement, aX, aY, aObserver = null) {
 // We also wait for the mouse move event to be processed before sending the
 // wheel event, otherwise there is a chance they might get reordered, and
 // we have the transaction problem again.
-function moveMouseAndScrollWheelOver(element, dx, dy, testDriver) {
+function moveMouseAndScrollWheelOver(element, dx, dy, testDriver, waitForScroll = true) {
   return synthesizeNativeMouseMoveAndWaitForMoveEvent(element, dx, dy, function() {
-    synthesizeNativeWheelAndWaitForScrollEvent(element, dx, dy, 0, -10, testDriver);
+    if (waitForScroll) {
+      synthesizeNativeWheelAndWaitForScrollEvent(element, dx, dy, 0, -10, testDriver);
+    } else {
+      synthesizeNativeWheelAndWaitForWheelEvent(element, dx, dy, 0, -10, testDriver);
+    }
   });
 }
diff --git a/gfx/layers/apz/test/mochitest/helper_bug1271432.html b/gfx/layers/apz/test/mochitest/helper_bug1271432.html
index c2e3237ef039..8234b82327d0 100644
--- a/gfx/layers/apz/test/mochitest/helper_bug1271432.html
+++ b/gfx/layers/apz/test/mochitest/helper_bug1271432.html
@@ -12,8 +12,7 @@ function* test(testDriver) {
   is(window.scrollY, 0, "Initial page scroll position should be 0");
   is(scrollerPos, 0, "Initial scroller position should be 0");
 
-  yield synthesizeNativeMouseMoveAndWaitForMoveEvent(scroller, dx, dy, testDriver);
-  yield synthesizeNativeWheelAndWaitForScrollEvent(scroller, dx, dy, 0, -10, testDriver);
+  yield moveMouseAndScrollWheelOver(scroller, dx, dy, testDriver);
 
   is(window.scrollY, 0, "Page scroll position should still be 0");
   ok(scroller.scrollTop > scrollerPos, "Scroller should have scrolled");
@@ -24,10 +23,7 @@ function* test(testDriver) {
   });
   scrollerPos = scroller.scrollTop;
 
-  // The mouse is already at the right position. If we call scrollWheelOver it
-  // hangs on windows waiting for the mouse-move, so instead we just synthesize
-  // the wheel directly.
-  yield synthesizeNativeWheelAndWaitForScrollEvent(scroller, dx, dy, 0, -10, testDriver);
+  yield moveMouseAndScrollWheelOver(scroller, dx, dy, testDriver);
   is(window.scrollY, 0, "Page scroll position should still be 0 after layerization");
   ok(scroller.scrollTop > scrollerPos, "Scroller should have continued scrolling");
 }
diff --git a/gfx/layers/apz/test/mochitest/helper_scroll_on_position_fixed.html b/gfx/layers/apz/test/mochitest/helper_scroll_on_position_fixed.html
index 12f9cb001bbc..b9d187faf6fe 100644
--- a/gfx/layers/apz/test/mochitest/helper_scroll_on_position_fixed.html
+++ b/gfx/layers/apz/test/mochitest/helper_scroll_on_position_fixed.html
@@ -30,10 +30,7 @@ function* test(testDriver) {
     flushApzRepaints(testDriver);
   });
   scrollPos = fpos.scrollTop;
-  // The mouse is already at the right position. If we call moveMouseAndScrollWheelOver it
-  // hangs on windows waiting for the mouse-move, so instead we just synthesize
-  // the wheel directly.
-  yield synthesizeNativeWheelAndWaitForScrollEvent(fpos, 50, 150, 0, -10, testDriver);
+  yield moveMouseAndScrollWheelOver(fpos, 50, 150, testDriver);
   ok(fpos.scrollTop > scrollPos, "scrollable item inside fixed-pos element scrolled after layerization");
 
   // same, but using the top-level window's position:sticky element
diff --git a/gfx/layers/apz/test/mochitest/test_layerization.html b/gfx/layers/apz/test/mochitest/test_layerization.html
index 5100f7375ac8..13af614328be 100644
--- a/gfx/layers/apz/test/mochitest/test_layerization.html
+++ b/gfx/layers/apz/test/mochitest/test_layerization.html
@@ -55,22 +55,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1173580
 
 // Scroll the mouse wheel over |element|.
 function scrollWheelOver(element, waitForScroll, testDriver) {
-  var x = 10;
-  var y = 10;
-  // Move the mouse to the desired wheel location.
-  // Not doing so can result in the wheel events from two consecutive
-  // scrollWheelOver() calls on different elements being incorrectly considered
-  // as part of the same wheel transaction.
-  // We also wait for the mouse move event to be processed before sending the
-  // wheel event, otherwise there is a chance they might get reordered, and
-  // we have the transaction problem again.
-  synthesizeNativeMouseMoveAndWaitForMoveEvent(element, x, y, function() {
-    if (waitForScroll) {
-      synthesizeNativeWheelAndWaitForScrollEvent(element, x, y, 0, -10, testDriver);
-    } else {
-      synthesizeNativeWheelAndWaitForWheelEvent(element, x, y, 0, -10, testDriver);
-    }
-  });
+  moveMouseAndScrollWheelOver(element, 10, 10, testDriver, waitForScroll);
 }
 
 var utils;