diff --git a/devtools/shared/css/generated/properties-db.js b/devtools/shared/css/generated/properties-db.js
index 52bf697fa..9eabcd1ef 100644
--- a/devtools/shared/css/generated/properties-db.js
+++ b/devtools/shared/css/generated/properties-db.js
@@ -1222,7 +1222,7 @@ exports.CSS_PROPERTIES = {
   "-moz-tab-size": {
     "isInherited": true,
     "subproperties": [
-      "-moz-tab-size"
+      "tab-size"
     ],
     "supports": [
       6,
@@ -3032,7 +3032,7 @@ exports.CSS_PROPERTIES = {
       "stroke-opacity",
       "stroke-width",
       "-x-system-font",
-      "-moz-tab-size",
+      "tab-size",
       "table-layout",
       "text-align",
       "text-align-last",
@@ -8574,6 +8574,23 @@ exports.CSS_PROPERTIES = {
       "unset"
     ]
   },
+  "tab-size": {
+    "isInherited": true,
+    "subproperties": [
+      "tab-size"
+    ],
+    "supports": [
+      6,
+      7
+    ],
+    "values": [
+      "-moz-calc",
+      "calc",
+      "inherit",
+      "initial",
+      "unset"
+    ]
+  },
   "table-layout": {
     "isInherited": false,
     "subproperties": [
diff --git a/layout/style/nsCSSPropAliasList.h b/layout/style/nsCSSPropAliasList.h
index 7f74ff1c6..ca8c32f35 100644
--- a/layout/style/nsCSSPropAliasList.h
+++ b/layout/style/nsCSSPropAliasList.h
@@ -219,6 +219,10 @@ CSS_PROP_ALIAS(-moz-columns,
                columns,
                MozColumns,
                "")
+CSS_PROP_ALIAS(-moz-tab-size,
+	       tab_size,
+	       MozTabSize,
+	       "")
 
 #define WEBKIT_PREFIX_PREF "layout.css.prefixes.webkit"
 
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index fcfc45a1a..fdce6a421 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -3879,9 +3879,9 @@ CSS_PROP_FONT(
     eStyleAnimType_None)
 #endif // CSS_PROP_LIST_EXCLUDE_INTERNAL
 CSS_PROP_TEXT(
-    -moz-tab-size,
-    _moz_tab_size,
-    CSS_PROP_DOMPROP_PREFIXED(TabSize),
+    tab-size,
+    tab_size,
+    TabSize,
     CSS_PROPERTY_PARSE_VALUE |
         CSS_PROPERTY_VALUE_NONNEGATIVE,
     "",
diff --git a/layout/style/nsComputedDOMStylePropertyList.h b/layout/style/nsComputedDOMStylePropertyList.h
index a4d4264f4..4d17a420e 100644
--- a/layout/style/nsComputedDOMStylePropertyList.h
+++ b/layout/style/nsComputedDOMStylePropertyList.h
@@ -228,6 +228,7 @@ COMPUTED_STYLE_PROP(scroll_snap_type_x,            ScrollSnapTypeX)
 COMPUTED_STYLE_PROP(scroll_snap_type_y,            ScrollSnapTypeY)
 COMPUTED_STYLE_PROP(shape_outside,                 ShapeOutside)
 //// COMPUTED_STYLE_PROP(size,                     Size)
+COMPUTED_STYLE_PROP(tab_size,			   TabSize)
 COMPUTED_STYLE_PROP(table_layout,                  TableLayout)
 COMPUTED_STYLE_PROP(text_align,                    TextAlign)
 COMPUTED_STYLE_PROP(text_align_last,               TextAlignLast)
@@ -295,7 +296,6 @@ COMPUTED_STYLE_PROP(_moz_outline_radius_bottomright,OutlineRadiusBottomRight)
 COMPUTED_STYLE_PROP(_moz_outline_radius_topleft,    OutlineRadiusTopLeft)
 COMPUTED_STYLE_PROP(_moz_outline_radius_topright,   OutlineRadiusTopRight)
 COMPUTED_STYLE_PROP(_moz_stack_sizing,             StackSizing)
-COMPUTED_STYLE_PROP(_moz_tab_size,                 TabSize)
 COMPUTED_STYLE_PROP(_moz_text_size_adjust,         TextSizeAdjust)
 COMPUTED_STYLE_PROP(_moz_user_focus,               UserFocus)
 COMPUTED_STYLE_PROP(_moz_user_input,               UserInput)
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 26f4e928d..cdadeb37b 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -1918,14 +1918,21 @@ var gCSSProperties = {
     other_values: [ "ignore" ],
     invalid_values: []
   },
-  "-moz-tab-size": {
-    domProp: "MozTabSize",
+  "tab-size": {
+    domProp: "TabSize",
     inherited: true,
     type: CSS_TYPE_LONGHAND,
     initial_values: [ "8" ],
     other_values: [ "0", "2.5", "3", "99", "12000", "0px", "1em", "calc(1px + 1em)", "calc(1px - 2px)", "calc(1 + 1)", "calc(-2.5)" ],
     invalid_values: [ "9%", "calc(9% + 1px)", "calc(1 + 1em)", "-1", "-808", "auto" ]
   },
+  "-moz-tab-size": {
+    domProp: "MozTabSize",
+    inherited: true,
+    type: CSS_TYPE_SHORTHAND_AND_LONGHAND
+    alias_for: "tab-size",
+    subproperties: [ "tab-size" ]
+  },
   "-moz-text-size-adjust": {
     domProp: "MozTextSizeAdjust",
     inherited: true,
diff --git a/parser/html/nsHtml5ViewSourceUtils.cpp b/parser/html/nsHtml5ViewSourceUtils.cpp
index b2f635bff..910a6691e 100644
--- a/parser/html/nsHtml5ViewSourceUtils.cpp
+++ b/parser/html/nsHtml5ViewSourceUtils.cpp
@@ -31,7 +31,7 @@ nsHtml5ViewSourceUtils::NewBodyAttributes()
   int32_t tabSize = mozilla::Preferences::GetInt("view_source.tab_size", 4);
   if (tabSize > 0) {
     nsString style;
-    style.AssignASCII("-moz-tab-size: ");
+    style.AssignASCII("tab-size: ");
     style.AppendInt(tabSize);
     bodyAttrs->addAttribute(
       nsHtml5AttributeName::ATTR_STYLE, nsHtml5String::FromString(style), -1);