diff --git a/src/core.js b/src/core.js
index 0211808c5..fcbd1c358 100644
--- a/src/core.js
+++ b/src/core.js
@@ -17,7 +17,8 @@ var jQuery = function( selector, context ) {
 
 	// A simple way to check for HTML strings or ID strings
 	// (both of which we optimize for)
-	quickExpr = /^(?:[^<]*(<[\w\W]+>)[^>]*$|#([\w\-]+)$)/,
+	quickExpr = /^(?:[^<]*(<[\w\W]+>)[^>]*$|#([\w\-]*)$)/,
+
 
 	// Is it a simple selector
 	isSimple = /^.[^:#\[\.,]*$/,
diff --git a/test/unit/core.js b/test/unit/core.js
index 9367ab10d..2563f17cb 100644
--- a/test/unit/core.js
+++ b/test/unit/core.js
@@ -12,7 +12,7 @@ test("Basic requirements", function() {
 });
 
 test("jQuery()", function() {
-	expect(24);
+	expect(25);
 
 	strictEqual( commonJSDefined, jQuery, "CommonJS registered (Bug #7102)" );
 
@@ -22,6 +22,7 @@ test("jQuery()", function() {
 	equals( jQuery(undefined).length, 0, "jQuery(undefined) === jQuery([])" );
 	equals( jQuery(null).length, 0, "jQuery(null) === jQuery([])" );
 	equals( jQuery("").length, 0, "jQuery('') === jQuery([])" );
+	equals( jQuery("#").length, 0, "jQuery('#') === jQuery([])" );
 
 	var obj = jQuery("div")
 	equals( jQuery(obj).selector, "div", "jQuery(jQueryObj) == jQueryObj" );