diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 8f667faef2..40e938546c 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -164,6 +164,7 @@
 		<li>[Fix] Remove redundant SQL query from ucp.php. (Bug #40305)</li>
 		<li>[Fix] Reorder frame order of animated subsilver2 topic icons to be useful when animation is disabled. (Bug #29385 - Patch by prototech)</li>
 		<li>[Fix] Ensure user errors are displayed regardless of PHP settings. (Bug #47505)</li>
+		<li>[Fix] Permit null values for non-required integer custom profile fields and ensure zero complies with the range limits. (Bug #40925)</li>
 		<li>[Change] Change the data format of the default file ACM to be more secure from tampering and have better performance.</li>
 		<li>[Change] Add index on log_time to the log table to prevent slowdown on boards with many log entries. (Bug #44665 - Patch by bantu)</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/functions_profile_fields.php b/phpBB/includes/functions_profile_fields.php
index bb1ec476c4..9e356414a9 100644
--- a/phpBB/includes/functions_profile_fields.php
+++ b/phpBB/includes/functions_profile_fields.php
@@ -90,18 +90,6 @@ class custom_profile
 	*/
 	function validate_profile_field($field_type, &$field_value, $field_data)
 	{
-		switch ($field_type)
-		{
-			case FIELD_INT:
-			case FIELD_DROPDOWN:
-				$field_value = (int) $field_value;
-			break;
-
-			case FIELD_BOOL:
-				$field_value = (bool) $field_value;
-			break;
-		}
-
 		switch ($field_type)
 		{
 			case FIELD_DATE:
@@ -133,6 +121,8 @@ class custom_profile
 			break;
 
 			case FIELD_BOOL:
+				$field_value = (bool) $field_value;
+			
 				if (!$field_value && $field_data['field_required'])
 				{
 					return 'FIELD_REQUIRED';
@@ -140,10 +130,12 @@ class custom_profile
 			break;
 
 			case FIELD_INT:
-				if (empty($field_value) && !$field_data['field_required'])
+				if (trim($field_value) === '' && !$field_data['field_required'])
 				{
 					return false;
 				}
+				
+				$field_value = (int) $field_value;
 
 				if ($field_value < $field_data['field_minlen'])
 				{
@@ -156,6 +148,8 @@ class custom_profile
 			break;
 
 			case FIELD_DROPDOWN:
+				$field_value = (int) $field_value;
+			
 				if ($field_value == $field_data['field_novalue'] && $field_data['field_required'])
 				{
 					return 'FIELD_REQUIRED';
@@ -514,7 +508,7 @@ class custom_profile
 		switch ($this->profile_types[$field_type])
 		{
 			case 'int':
-				if ($value == '')
+				if ($value === '')
 				{
 					return NULL;
 				}
@@ -644,7 +638,7 @@ class custom_profile
 				}
 			}
 
-			return (is_null($value)) ? '' : (int) $value;
+			return (is_null($value) || $value === '') ? '' : (int) $value;
 		}
 		else
 		{