diff --git a/assert/assertions.go b/assert/assertions.go
index 6ab0ec347..d987e2866 100644
--- a/assert/assertions.go
+++ b/assert/assertions.go
@@ -753,11 +753,11 @@ func Len(t TestingT, object interface{}, length int, msgAndArgs ...interface{})
 	}
 	ok, l := getLen(object)
 	if !ok {
-		return Fail(t, fmt.Sprintf("\"%s\" could not be applied builtin len()", object), msgAndArgs...)
+		return Fail(t, fmt.Sprintf(`"%s" could not be applied builtin len()`, spew.Sdump(object)), msgAndArgs...)
 	}
 
 	if l != length {
-		return Fail(t, fmt.Sprintf("\"%s\" should have %d item(s), but has %d", object, length, l), msgAndArgs...)
+		return Fail(t, fmt.Sprintf(`"%s" should have %d item(s), but has %d`, spew.Sdump(object), length, l), msgAndArgs...)
 	}
 	return true
 }