diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 9acf4561ae5..ae4ce1053e1 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -2350,7 +2350,7 @@ CSS_PROP_DISPLAY(
     perspective,
     CSS_PROP_DOMPROP_PREFIXED(Perspective),
     CSS_PROPERTY_PARSE_VALUE,
-    VARIANT_NONE | VARIANT_INHERIT | VARIANT_LENGTH,
+    VARIANT_NONE | VARIANT_INHERIT | VARIANT_LENGTH | VARIANT_POSITIVE_LENGTH,
     nsnull,
     offsetof(nsStyleDisplay, mChildPerspective),
     eStyleAnimType_Coord)
diff --git a/layout/style/test/property_database.js b/layout/style/test/property_database.js
index 2951de6d8cc..22f1281c79b 100644
--- a/layout/style/test/property_database.js
+++ b/layout/style/test/property_database.js
@@ -1082,9 +1082,9 @@ var gCSSProperties = {
 		domProp: "MozPerspective",
 		inherited: false,
 		type: CSS_TYPE_LONGHAND,
-		initial_values: [ "none", "0" ],
-		other_values: [ "1000px", "500.2px", "-100px", "-27.2em" ],
-		invalid_values: [ "pants", "200" ]
+		initial_values: [ "none" ],
+		other_values: [ "1000px", "500.2px" ],
+		invalid_values: [ "pants", "200", "0", "-100px", "-27.2em" ]
 	},
     "-moz-backface-visibility": {
         domProp: "MozBackfaceVisibility",