diff --git a/lib/test.js b/lib/test.js
index 4dcc7f8b..78b9763d 100644
--- a/lib/test.js
+++ b/lib/test.js
@@ -458,7 +458,7 @@ Test.prototype['throws'] = function (fn, expected, msg, extra) {
         caught.error = caught.error.constructor;
     }
 
-    this._assert(passed, {
+    this._assert(typeof fn === 'function' && passed, {
         message : defined(msg, 'should throw'),
         operator : 'throws',
         actual : caught && caught.error,
diff --git a/test/throws.js b/test/throws.js
index ec91fb8d..b8cf056f 100644
--- a/test/throws.js
+++ b/test/throws.js
@@ -1,20 +1,135 @@
-var test = require('../');
+var tape = require('../');
+var tap = require('tap');
+var concat = require('concat-stream');
 
 function fn() {
     throw new TypeError('RegExp');
 }
 
-test('throws', function (t) {
+function getNonFunctionMessage(fn) {
+    try {
+        fn();
+    } catch (e) {
+        return e.message;
+    }
+}
+
+tape('throws', function (t) {
     t.throws(fn);
     t.end();
 });
 
-test('throws (RegExp match)', function (t) {
+tape('throws (RegExp match)', function (t) {
     t.throws(fn, /RegExp/);
     t.end();
 });
 
-test('throws (Function match)', function (t) {
+tape('throws (Function match)', function (t) {
     t.throws(fn, TypeError);
     t.end();
 });
+
+tap.test('failures', function (tt) {
+    tt.plan(1);
+
+    var test = tape.createHarness();
+    test.createStream().pipe(concat(function (body) {
+        tt.equal(
+            body.toString('utf8'),
+            'TAP version 13\n'
+           + '# non functions\n'
+           + 'not ok 1 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage() + "] message: '" + getNonFunctionMessage() + "' }\n"
+           + '  ...\n'
+           + 'not ok 2 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage(null) + "] message: '" + getNonFunctionMessage(null) + "' }\n"
+           + '  ...\n'
+           + 'not ok 3 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage(true) + "] message: '" + getNonFunctionMessage(true) + "' }\n"
+           + '  ...\n'
+           + 'not ok 4 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage(false) + "] message: '" + getNonFunctionMessage(false) + "' }\n"
+           + '  ...\n'
+           + 'not ok 5 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage('abc') + "] message: '" + getNonFunctionMessage('abc') + "' }\n"
+           + '  ...\n'
+           + 'not ok 6 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage(/a/g) + "] message: '" + getNonFunctionMessage(/a/g) + "' }\n"
+           + '  ...\n'
+           + 'not ok 7 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage([]) + "] message: '" + getNonFunctionMessage([]) + "' }\n"
+           + '  ...\n'
+           + 'not ok 8 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: |-\n'
+           + '      undefined\n'
+           + '    actual: |-\n'
+           + "      { [TypeError: " + getNonFunctionMessage({}) + "] message: '" + getNonFunctionMessage({}) + "' }\n"
+           + '  ...\n'
+           + '# function\n'
+           + 'not ok 9 should throw\n'
+           + '  ---\n'
+           + '    operator: throws\n'
+           + '    expected: undefined\n'
+           + '    actual:   undefined\n'
+           + '  ...\n\n'
+           + '1..9\n'
+           + '# tests 9\n'
+           + '# pass  0\n'
+           + '# fail  9\n'
+        );
+    }));
+
+    test('non functions', function (t) {
+        t.plan(8);
+        t.throws();
+        t.throws(null);
+        t.throws(true);
+        t.throws(false);
+        t.throws('abc');
+        t.throws(/a/g);
+        t.throws([]);
+        t.throws({});
+    });
+
+    test('function', function (t) {
+        t.plan(1);
+        t.throws(function () {});
+    });
+});