diff --git a/assert/assertions.go b/assert/assertions.go
index 2457a0d..2ca22eb 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -352,6 +352,19 @@ func Equal(t TestingT, expected, actual interface{}, msgAndArgs ...interface{})
 
 }
 
+// validateEqualArgs checks whether provided arguments can be safely used in the
+// Equal/NotEqual functions.
+func validateEqualArgs(expected, actual interface{}) error {
+	if expected == nil && actual == nil {
+		return nil
+	}
+
+	if isFunction(expected) || isFunction(actual) {
+		return errors.New("cannot take func type as argument")
+	}
+	return nil
+}
+
 // Same asserts that two pointers reference the same object.
 //
 //    assert.Same(t, ptr1, ptr2)
@@ -1526,15 +1539,6 @@ func diff(expected interface{}, actual interface{}) string {
 	return "\n\nDiff:\n" + diff
 }
 
-// validateEqualArgs checks whether provided arguments can be safely used in the
-// Equal/NotEqual functions.
-func validateEqualArgs(expected, actual interface{}) error {
-	if isFunction(expected) || isFunction(actual) {
-		return errors.New("cannot take func type as argument")
-	}
-	return nil
-}
-
 func isFunction(arg interface{}) bool {
 	if arg == nil {
 		return false
diff --git a/assert/assertions_test.go b/assert/assertions_test.go
index f398820..b851116 100644
--- a/assert/assertions_test.go
+++ b/assert/assertions_test.go
@@ -131,6 +131,12 @@ func TestObjectsAreEqual(t *testing.T) {
 	if ObjectsAreEqual(0.1, 0) {
 		t.Error("objectsAreEqual should return false")
 	}
+	if ObjectsAreEqual(time.Now, time.Now) {
+		t.Error("objectsAreEqual should return false")
+	}
+	if ObjectsAreEqual(func() {}, func() {}) {
+		t.Error("objectsAreEqual should return false")
+	}
 	if ObjectsAreEqual(uint32(10), int32(10)) {
 		t.Error("objectsAreEqual should return false")
 	}
@@ -515,6 +521,9 @@ func TestNotEqual(t *testing.T) {
 	if NotEqual(mockT, funcA, funcB) {
 		t.Error("NotEqual should return false")
 	}
+	if NotEqual(mockT, nil, nil) {
+		t.Error("NotEqual should return false")
+	}
 
 	if NotEqual(mockT, "Hello World", "Hello World") {
 		t.Error("NotEqual should return false")
@@ -850,8 +859,8 @@ func TestPanicsWithError(t *testing.T) {
 
 	mockT := new(testing.T)
 
-	if !PanicsWithError(mockT, "Panic!", func() {
-		panic(errors.New("Panic!"))
+	if !PanicsWithError(mockT, "panic", func() {
+		panic(errors.New("panic"))
 	}) {
 		t.Error("PanicsWithError should return true")
 	}
@@ -862,13 +871,13 @@ func TestPanicsWithError(t *testing.T) {
 	}
 
 	if PanicsWithError(mockT, "at the disco", func() {
-		panic(errors.New("Panic!"))
+		panic(errors.New("panic"))
 	}) {
 		t.Error("PanicsWithError should return false")
 	}
 
 	if PanicsWithError(mockT, "Panic!", func() {
-		panic("Panic!")
+		panic("panic")
 	}) {
 		t.Error("PanicsWithError should return false")
 	}
@@ -1922,11 +1931,6 @@ func BenchmarkBytesEqual(b *testing.B) {
 	}
 }
 
-func TestEqualArgsValidation(t *testing.T) {
-	err := validateEqualArgs(time.Now, time.Now)
-	EqualError(t, err, "cannot take func type as argument")
-}
-
 func ExampleComparisonAssertionFunc() {
 	t := &testing.T{} // provided by test
 
@@ -2153,3 +2157,17 @@ func TestEventuallyIssue805(t *testing.T) {
 		False(t, Eventually(mockT, condition, time.Millisecond, time.Microsecond))
 	})
 }
+
+func Test_validateEqualArgs(t *testing.T) {
+	if validateEqualArgs(func() {}, func() {}) == nil {
+		t.Error("non-nil functions should error")
+	}
+
+	if validateEqualArgs(func() {}, func() {}) == nil {
+		t.Error("non-nil functions should error")
+	}
+
+	if validateEqualArgs(nil, nil) != nil {
+		t.Error("nil functions are equal")
+	}
+}