diff --git a/layout/reftests/columns/reftest.list b/layout/reftests/columns/reftest.list
index 9df2c76b5b09..464cb9986b4f 100644
--- a/layout/reftests/columns/reftest.list
+++ b/layout/reftests/columns/reftest.list
@@ -51,5 +51,5 @@ pref(layout.css.column-span.enabled,true) == first-line-first-letter.html first-
 default-preferences pref(layout.css.column-span.enabled,true)
 == min-width-2.html min-width-2-ref.html
 == column-balancing-nested-001.html column-balancing-nested-001-ref.html
-fails == zero-height-nondirty-reflow.html zero-height-nondirty-reflow-ref.html # bug 1565665
+== zero-height-nondirty-reflow.html zero-height-nondirty-reflow-ref.html
 default-preferences
diff --git a/layout/style/res/ua.css b/layout/style/res/ua.css
index b7c91ae4f8ff..288172e80e6e 100644
--- a/layout/style/res/ua.css
+++ b/layout/style/res/ua.css
@@ -256,8 +256,8 @@
   /* make unicode-bidi inherit, otherwise it has no effect on column boxes */
   unicode-bidi: inherit;
   text-overflow: inherit;
-  /* inherit the outer frame's display, otherwise we turn into an inline */
-  display: inherit;
+  /* Both -moz-column-set and -moz-column-content need to be blocks. */
+  display: block;
   /* -moz-column-set and -moz-column-content's max block size cannot exceed
    * ColumnSetWrapperFrame's block size. */
   max-block-size: 100%;
diff --git a/testing/web-platform/meta/css/css-multicol/multicol-gap-percentage-001.html.ini b/testing/web-platform/meta/css/css-multicol/multicol-gap-percentage-001.html.ini
index ec1884600973..878b2af2d722 100644
--- a/testing/web-platform/meta/css/css-multicol/multicol-gap-percentage-001.html.ini
+++ b/testing/web-platform/meta/css/css-multicol/multicol-gap-percentage-001.html.ini
@@ -1,7 +1,2 @@
 [multicol-gap-percentage-001.html]
-  [.multicol 4]
-    expected: FAIL
-
-  [.multicol 6]
-    expected: FAIL
-
+  prefs: [layout.css.column-span.enabled:true]