diff --git a/assert/assertions.go b/assert/assertions.go
index 60cfc69..d0705d5 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -865,9 +865,8 @@ func NoError(t TestingT, err error, msgAndArgs ...interface{}) bool {
 // Returns whether the assertion was successful (true) or not (false).
 func Error(t TestingT, err error, msgAndArgs ...interface{}) bool {
 
-	message := messageFromMsgAndArgs(msgAndArgs...)
 	if err == nil {
-		return Fail(t, "An error is expected but got nil. %s", message)
+		return Fail(t, "An error is expected but got nil.", msgAndArgs...)
 	}
 
 	return true
@@ -877,9 +876,7 @@ func Error(t TestingT, err error, msgAndArgs ...interface{}) bool {
 // and that it is equal to the provided error.
 //
 //   actualObj, err := SomeFunction()
-//   if assert.Error(t, err, "An error was expected") {
-//	   assert.Equal(t, err, expectedError)
-//   }
+//   assert.EqualError(t, err,  expectedErrorString, "An error was expected")
 //
 // Returns whether the assertion was successful (true) or not (false).
 func EqualError(t TestingT, theError error, errString string, msgAndArgs ...interface{}) bool {
diff --git a/assert/http_assertions.go b/assert/http_assertions.go
index e1b9442..fa7ab89 100644
--- a/assert/http_assertions.go
+++ b/assert/http_assertions.go
@@ -99,7 +99,7 @@ func HTTPBodyNotContains(t TestingT, handler http.HandlerFunc, method, url strin
 
 	contains := strings.Contains(body, fmt.Sprint(str))
 	if contains {
-		Fail(t, "Expected response body for %s to NOT contain \"%s\" but found \"%s\"", url+"?"+values.Encode(), str, body)
+		Fail(t, fmt.Sprintf("Expected response body for \"%s\" to NOT contain \"%s\" but found \"%s\"", url+"?"+values.Encode(), str, body))
 	}
 
 	return !contains