diff --git a/layout/html/document/src/ua.css b/layout/html/document/src/ua.css
index 1f02f2d8444..b1fc2dd9040 100644
--- a/layout/html/document/src/ua.css
+++ b/layout/html/document/src/ua.css
@@ -281,7 +281,7 @@ ABBR, ACRONYM, DEL, DFN, INS, Q, SPAN {
   display: inline;
 }
 INS { text-decoration: underline; }
-DEL { text-decoration: strike-through; }
+DEL { text-decoration: line-through; }
 DFN { font-style: italic; }
 SUB {
   display: inline;
diff --git a/layout/style/ua.css b/layout/style/ua.css
index 1f02f2d8444..b1fc2dd9040 100644
--- a/layout/style/ua.css
+++ b/layout/style/ua.css
@@ -281,7 +281,7 @@ ABBR, ACRONYM, DEL, DFN, INS, Q, SPAN {
   display: inline;
 }
 INS { text-decoration: underline; }
-DEL { text-decoration: strike-through; }
+DEL { text-decoration: line-through; }
 DFN { font-style: italic; }
 SUB {
   display: inline;