diff --git a/src/effects.js b/src/effects.js
index bb10b73f8..78f36827a 100644
--- a/src/effects.js
+++ b/src/effects.js
@@ -249,7 +249,7 @@ jQuery.Animation = jQuery.extend( Animation, {
 
 function defaultPrefilter( elem, props, opts ) {
 	/* jshint validthis: true */
-	var index, prop, value, toggle, tween, hooks, oldfire,
+	var prop, value, toggle, tween, hooks, oldfire,
 		anim = this,
 		orig = {},
 		style = elem.style,
@@ -310,21 +310,21 @@ function defaultPrefilter( elem, props, opts ) {
 
 
 	// show/hide pass
-	for ( index in props ) {
-		value = props[ index ];
+	for ( prop in props ) {
+		value = props[ prop ];
 		if ( rfxtypes.exec( value ) ) {
-			delete props[ index ];
+			delete props[ prop ];
 			toggle = toggle || value === "toggle";
 			if ( value === ( hidden ? "hide" : "show" ) ) {
 
 				// If there is dataShow left over from a stopped hide or show and we are going to proceed with show, we should pretend to be hidden
-				if ( value === "show" && dataShow && dataShow[ index ] !== undefined ) {
+				if ( value === "show" && dataShow && dataShow[ prop ] !== undefined ) {
 					hidden = true;
 				} else {
 					continue;
 				}
 			}
-			orig[ index ] = dataShow && dataShow[ index ] || jQuery.style( elem, index );
+			orig[ prop ] = dataShow && dataShow[ prop ] || jQuery.style( elem, prop );
 		}
 	}
 
diff --git a/test/unit/effects.js b/test/unit/effects.js
index 47bc9b4b6..d59ff84a6 100644
--- a/test/unit/effects.js
+++ b/test/unit/effects.js
@@ -1379,8 +1379,8 @@ test("line-height animates correctly (#13855)", function() {
 		animated = jQuery(
 			"<p style='line-height: 4;'>unitless</p>" +
 			"<p style='line-height: 50px;'>px</p>" +
-			"<p style='line-height: 120%;'>percent</p>" +
-			"<p style='line-height: 1.5em;'>em</p>"
+			"<p style='line-height: 420%;'>percent</p>" +
+			"<p style='line-height: 2.5em;'>em</p>"
 		).appendTo("#qunit-fixture"),
 		initialHeight = jQuery.map( animated, function( el ) {
 			return jQuery( el ).height();