diff --git a/src/core.js b/src/core.js
index 93fe25568..b32519893 100644
--- a/src/core.js
+++ b/src/core.js
@@ -1248,6 +1248,12 @@ $.extend( $.validator, {
 
 		for ( method in $.validator.methods ) {
 			value = $element.data( "rule" + method.charAt( 0 ).toUpperCase() + method.substring( 1 ).toLowerCase() );
+
+			// Cast empty attributes like `data-rule-required` to `true`
+			if ( value === "" ) {
+				value = true;
+			}
+
 			this.normalizeAttributeRule( rules, type, method, value );
 		}
 		return rules;
diff --git a/test/index.html b/test/index.html
index 0079aa7d9..d02732856 100644
--- a/test/index.html
+++ b/test/index.html
@@ -277,7 +277,9 @@ <h3></h3>
 		<input id="v2-i4" name="v2-i4" class="required" minlength="2">
 		<input id="v2-i5" name="v2-i5" class="required" minlength="2" maxlength="5" customMethod1="123">
 		<input id="v2-i6" name="v2-i6" class="required customMethod2" data-rule-maxlength="5" data-rule-minlength="2">
-		<input id="v2-i7" name="v2-i7">
+		<input id="v2-i7" name="v2-i7" data-rule-number data-rule-required>
+		<input id="v2-i8" name="v2-i8" data-rule-number="" data-rule-required="">
+		<input id="v2-i9" name="v2-i9">
 	</form>
 	<form id="checkables">
 		<input type="checkbox" id="checkable1" name="checkablesgroup" class="required">
diff --git a/test/rules.js b/test/rules.js
index 1be57bf49..178f810b2 100644
--- a/test/rules.js
+++ b/test/rules.js
@@ -157,7 +157,7 @@ QUnit.test( "rules(), class and attribute combinations", function( assert ) {
 
 	$( "#v2" ).validate( {
 		rules: {
-			"v2-i7": {
+			"v2-i9": {
 				required: true,
 				minlength: 2,
 				customMethod: true
@@ -173,8 +173,10 @@ QUnit.test( "rules(), class and attribute combinations", function( assert ) {
 	jQuery.validator.autoCreateRanges = true;
 	assert.deepEqual( $( "#v2-i5" ).rules(), { required: true, customMethod1: "123", rangelength: [ 2, 5 ] } );
 	assert.deepEqual( $( "#v2-i6" ).rules(), { required: true, customMethod2: true, rangelength: [ 2, 5 ] } );
+	assert.deepEqual( $( "#v2-i7" ).rules(), { required: true, number: true } );
+	assert.deepEqual( $( "#v2-i8" ).rules(), { required: true, number: true } );
 	jQuery.validator.autoCreateRanges = false;
-	assert.deepEqual( $( "#v2-i7" ).rules(), { required: true, minlength: 2, customMethod: true } );
+	assert.deepEqual( $( "#v2-i9" ).rules(), { required: true, minlength: 2, customMethod: true } );
 
 	delete $.validator.methods.customMethod1;
 	delete $.validator.messages.customMethod1;