diff --git a/ui/jquery.ui.core.js b/ui/jquery.ui.core.js
index 1d002ecea..3c9f90054 100644
--- a/ui/jquery.ui.core.js
+++ b/ui/jquery.ui.core.js
@@ -131,49 +131,52 @@ $.fn.extend({
 	}
 });
 
-$.each( [ "Width", "Height" ], function( i, name ) {
-	var side = name === "Width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ],
-		type = name.toLowerCase(),
-		orig = {
-			innerWidth: $.fn.innerWidth,
-			innerHeight: $.fn.innerHeight,
-			outerWidth: $.fn.outerWidth,
-			outerHeight: $.fn.outerHeight
+// support: jQuery <1.8
+if ( !$( "<a>" ).outerWidth( 1 ).jquery ) {
+	$.each( [ "Width", "Height" ], function( i, name ) {
+		var side = name === "Width" ? [ "Left", "Right" ] : [ "Top", "Bottom" ],
+			type = name.toLowerCase(),
+			orig = {
+				innerWidth: $.fn.innerWidth,
+				innerHeight: $.fn.innerHeight,
+				outerWidth: $.fn.outerWidth,
+				outerHeight: $.fn.outerHeight
+			};
+
+		function reduce( elem, size, border, margin ) {
+			$.each( side, function() {
+				size -= parseFloat( $.curCSS( elem, "padding" + this, true) ) || 0;
+				if ( border ) {
+					size -= parseFloat( $.curCSS( elem, "border" + this + "Width", true) ) || 0;
+				}
+				if ( margin ) {
+					size -= parseFloat( $.curCSS( elem, "margin" + this, true) ) || 0;
+				}
+			});
+			return size;
+		}
+
+		$.fn[ "inner" + name ] = function( size ) {
+			if ( size === undefined ) {
+				return orig[ "inner" + name ].call( this );
+			}
+
+			return this.each(function() {
+				$( this ).css( type, reduce( this, size ) + "px" );
+			});
 		};
 
-	function reduce( elem, size, border, margin ) {
-		$.each( side, function() {
-			size -= parseFloat( $.curCSS( elem, "padding" + this, true) ) || 0;
-			if ( border ) {
-				size -= parseFloat( $.curCSS( elem, "border" + this + "Width", true) ) || 0;
+		$.fn[ "outer" + name] = function( size, margin ) {
+			if ( typeof size !== "number" ) {
+				return orig[ "outer" + name ].call( this, size );
 			}
-			if ( margin ) {
-				size -= parseFloat( $.curCSS( elem, "margin" + this, true) ) || 0;
-			}
-		});
-		return size;
-	}
 
-	$.fn[ "inner" + name ] = function( size ) {
-		if ( size === undefined ) {
-			return orig[ "inner" + name ].call( this );
-		}
-
-		return this.each(function() {
-			$( this ).css( type, reduce( this, size ) + "px" );
-		});
-	};
-
-	$.fn[ "outer" + name] = function( size, margin ) {
-		if ( typeof size !== "number" ) {
-			return orig[ "outer" + name ].call( this, size );
-		}
-
-		return this.each(function() {
-			$( this).css( type, reduce( this, size, true, margin ) + "px" );
-		});
-	};
-});
+			return this.each(function() {
+				$( this).css( type, reduce( this, size, true, margin ) + "px" );
+			});
+		};
+	});
+}
 
 // selectors
 function focusable( element, isTabIndexNotNaN ) {