diff --git a/README.md b/README.md
index 1fe19ea..476e515 100644
--- a/README.md
+++ b/README.md
@@ -31,15 +31,10 @@ The `Collection` class implements `ArrayAccess` and `Countable` interface intern
 * `empty()`, `count()` can be used on instance of `Collection`.
 * Elements can be traversed via `foreach()` keyword.
 
-### 2.3 Comparing elements
-
-Some methods of `Collection` involves comparing two of its elements, which accepts `$flags` as one of its arguments.
-
-When these methods are being invoked, type of the very first element of the `Collection` represents that of all other ones. Make sure all elements are of the same type (numeric/string/others), otherwise you're likely to get a segfault.
-
 ### 2.4 Notes
 
 * The `Collection::xxxTo()` methods will preserve the original key-value pairs of destination `Collection` when keys collide.
+* Some methods of `Collection` involves comparing two of its elements, which accepts `$flags` as one of its arguments. When these methods are being invoked, make sure all elements are of the same type (numeric/string/others), otherwise you're likely to get a segfault.
 
 ## 3. Example
 
diff --git a/src/collections_methods.c b/src/collections_methods.c
index 3373cb3..5d09912 100644
--- a/src/collections_methods.c
+++ b/src/collections_methods.c
@@ -73,7 +73,6 @@
 #define ERR_BAD_SIZE() PHP_COLLECTIONS_ERROR(E_WARNING, "Size must be non-negative")
 #define ERR_BAD_INDEX() PHP_COLLECTIONS_ERROR(E_WARNING, "Index must be non-negative")
 #define ERR_NOT_ARITHMETIC() PHP_COLLECTIONS_ERROR(E_WARNING, "Elements should be int or double")
-#define ERR_BAD_FLAG() PHP_COLLECTIONS_ERROR(E_WARNING, "Invalid compare flag")
 #define ERR_SILENCED()
 
 #define ELEMENTS_VALIDATE(elements, err, err_then)                         \