diff --git a/lib/grunt/file.js b/lib/grunt/file.js
index c9a7eaeb6..9e545c426 100644
--- a/lib/grunt/file.js
+++ b/lib/grunt/file.js
@@ -51,6 +51,10 @@ var processPatterns = function(patterns, fn) {
   var result = [];
   // Iterate over flattened patterns array.
   grunt.util._.flatten(patterns).forEach(function(pattern) {
+    // If the pattern is a function, ignore it
+    if (typeof pattern === 'function') {
+      return;
+    }
     // If the first character is ! it should be omitted
     var exclusion = pattern.indexOf('!') === 0;
     // If the pattern is an exclusion, remove the !
diff --git a/test/grunt/file_test.js b/test/grunt/file_test.js
index 613ddc330..a0bdbbcde 100644
--- a/test/grunt/file_test.js
+++ b/test/grunt/file_test.js
@@ -232,6 +232,11 @@ exports['file.expand*'] = {
     test.deepEqual(grunt.file.expand(opts, ['js/foo.js', 'js/bar.js', 'js/baz.js']), ['js/foo.js', 'js/bar.js', 'js/baz.js'], 'non-matching filenames should be returned in result set.');
     test.done();
   },
+  'ignore functions within patterns': function(test) {
+    test.expect(1);
+    test.deepEqual(grunt.file.expand(['**/*.js', function() {}]), ['js/bar.js', 'js/foo.js'], 'functions passed in with patterns should be ignored.');
+    test.done();
+  },
 };
 
 exports['file.expandMapping'] = {