diff --git a/system/helpers/inflector_helper.php b/system/helpers/inflector_helper.php
index bd36c35..1c14f4a 100644
--- a/system/helpers/inflector_helper.php
+++ b/system/helpers/inflector_helper.php
@@ -63,7 +63,7 @@
 	{
 		$result = strval($str);
 
-		if ( ! is_countable($result))
+		if ( ! word_is_countable($result))
 		{
 			return $result;
 		}
@@ -128,7 +128,7 @@
 	{
 		$result = strval($str);
 
-		if ( ! is_countable($result))
+		if ( ! word_is_countable($result))
 		{
 			return $result;
 		}
@@ -226,7 +226,7 @@
 
 // --------------------------------------------------------------------
 
-if ( ! function_exists('is_countable'))
+if ( ! function_exists('word_is_countable'))
 {
 	/**
 	 * Checks if the given word has a plural version.
@@ -234,7 +234,7 @@
 	 * @param	string	$word	Word to check
 	 * @return	bool
 	 */
-	function is_countable($word)
+	function word_is_countable($word)
 	{
 		return ! in_array(
 			strtolower($word),
@@ -274,3 +274,14 @@
 		);
 	}
 }
+
+// --------------------------------------------------------------------
+
+if ( ! function_exists('is_countable'))
+{
+	function is_countable($word)
+	{
+		trigger_error('is_countable() is a native PHP function since version 7.3.0; use word_is_countable() instead', E_USER_WARNING);
+		return word_is_countable($word);
+	}
+}
diff --git a/tests/codeigniter/helpers/inflector_helper_test.php b/tests/codeigniter/helpers/inflector_helper_test.php
index 81ce5e3..3ec681b 100644
--- a/tests/codeigniter/helpers/inflector_helper_test.php
+++ b/tests/codeigniter/helpers/inflector_helper_test.php
@@ -93,4 +93,4 @@
 		}
 	}
 
-}
\ No newline at end of file
+}
diff --git a/user_guide_src/source/helpers/inflector_helper.rst b/user_guide_src/source/helpers/inflector_helper.rst
index df0c568..e3c0149 100644
--- a/user_guide_src/source/helpers/inflector_helper.rst
+++ b/user_guide_src/source/helpers/inflector_helper.rst
@@ -85,7 +85,7 @@
 
 		echo humanize('my-dog-spot', '-'); // Prints 'My Dog Spot'
 
-.. php:function:: is_countable($word)
+.. php:function:: word_is_countable($word)
 
 	:param	string	$word: Input string
 	:returns:	TRUE if the word is countable or FALSE if not
@@ -93,4 +93,7 @@
 
 	Checks if the given word has a plural version. Example::
 
-		is_countable('equipment'); // Returns FALSE
\ No newline at end of file
+		word_is_countable('equipment'); // Returns FALSE
+
+	.. note:: This function used to be called ``is_countable()`` in
+		in previous CodeIgniter versions.
diff --git a/user_guide_src/source/installation/upgrade_3110.rst b/user_guide_src/source/installation/upgrade_3110.rst
index a19f1e6..0e3b7c6 100644
--- a/user_guide_src/source/installation/upgrade_3110.rst
+++ b/user_guide_src/source/installation/upgrade_3110.rst
@@ -12,3 +12,14 @@
 
 .. note:: If you have any custom developed files in these directories,
 	please make copies of them first.
+
+Step 2: Check for calls to is_countable()
+==========================================
+
+
+PHP 7.3 introduces a native `is_countable() <https://secure.php.net/is_countable>`_
+function, which creates a name collision with the ``is_countable()`` function
+we've had in our :doc:`Inflector Helpers <../helpers/inflector_helper>`.
+
+If you've been using the helper function in question, you should now rename
+the calls to it to :php:func:`word_is_countable()`.