diff --git a/phpBB/includes/functions_upload.php b/phpBB/includes/functions_upload.php
index d5bbd80242..73ac1df2d2 100644
--- a/phpBB/includes/functions_upload.php
+++ b/phpBB/includes/functions_upload.php
@@ -751,6 +751,31 @@ class fileupload
 		$filename = $url['path'];
 		$filesize = 0;
 
+		$remote_max_filesize = $this->max_filesize;
+		if (!$remote_max_filesize)
+		{
+			$max_filesize = @ini_get('upload_max_filesize');
+
+			if (!empty($max_filesize))
+			{
+				$unit = strtolower(substr($max_filesize, -1, 1));
+				$remote_max_filesize = (int) $max_filesize;
+
+				switch ($unit)
+				{
+					case 'g':
+						$remote_max_filesize *= 1024;
+					// no break
+					case 'm':
+						$remote_max_filesize *= 1024;
+					// no break
+					case 'k':
+						$remote_max_filesize *= 1024;
+					// no break
+				}
+			}
+		}
+
 		$errno = 0;
 		$errstr = '';
 
@@ -779,9 +804,9 @@ class fileupload
 				$block = @fread($fsock, 1024);
 				$filesize += strlen($block);
 
-				if ($this->max_filesize && $filesize > $this->max_filesize)
+				if ($remote_max_filesize && $filesize > $remote_max_filesize)
 				{
-					$max_filesize = get_formatted_filesize($this->max_filesize, false);
+					$max_filesize = get_formatted_filesize($remote_max_filesize, false);
 
 					$file = new fileerror(sprintf($user->lang[$this->error_prefix . 'WRONG_FILESIZE'], $max_filesize['value'], $max_filesize['unit']));
 					return $file;
@@ -807,9 +832,9 @@ class fileupload
 					{
 						$length = (int) str_replace('content-length: ', '', strtolower($line));
 
-						if ($length && $length > $this->max_filesize)
+						if ($remote_max_filesize && $length && $length > $remote_max_filesize)
 						{
-							$max_filesize = get_formatted_filesize($this->max_filesize, false);
+							$max_filesize = get_formatted_filesize($remote_max_filesize, false);
 
 							$file = new fileerror(sprintf($user->lang[$this->error_prefix . 'WRONG_FILESIZE'], $max_filesize['value'], $max_filesize['unit']));
 							return $file;
diff --git a/phpBB/language/en/acp/attachments.php b/phpBB/language/en/acp/attachments.php
index 1821b8c867..6aeb3c2188 100644
--- a/phpBB/language/en/acp/attachments.php
+++ b/phpBB/language/en/acp/attachments.php
@@ -57,7 +57,7 @@ $lang = array_merge($lang, array(
 	'ATTACH_EXT_GROUPS_URL'				=> 'Extension groups',
 	'ATTACH_ID'							=> 'ID',
 	'ATTACH_MAX_FILESIZE'				=> 'Maximum file size',
-	'ATTACH_MAX_FILESIZE_EXPLAIN'		=> 'Maximum size of each file, with 0 being unlimited.',
+	'ATTACH_MAX_FILESIZE_EXPLAIN'		=> 'Maximum size of each file. If this value is 0, the uploadable filesize is only limited by your PHP configuration.',
 	'ATTACH_MAX_PM_FILESIZE'			=> 'Maximum file size messaging',
 	'ATTACH_MAX_PM_FILESIZE_EXPLAIN'	=> 'Maximum size of each file, with 0 being unlimited, attached to a private message.',
 	'ATTACH_ORPHAN_URL'					=> 'Orphan attachments',
diff --git a/phpBB/language/en/acp/board.php b/phpBB/language/en/acp/board.php
index 6e6d4302cd..f24376f8aa 100644
--- a/phpBB/language/en/acp/board.php
+++ b/phpBB/language/en/acp/board.php
@@ -108,7 +108,7 @@ $lang = array_merge($lang, array(
 	'MAX_AVATAR_SIZE'				=> 'Maximum avatar dimensions',
 	'MAX_AVATAR_SIZE_EXPLAIN'		=> 'Width x Height in pixels.',
 	'MAX_FILESIZE'					=> 'Maximum avatar file size',
-	'MAX_FILESIZE_EXPLAIN'			=> 'For uploaded avatar files.',
+	'MAX_FILESIZE_EXPLAIN'			=> 'For uploaded avatar files. If this value is 0, the uploaded filesize is only limited by your PHP configuration.',
 	'MIN_AVATAR_SIZE'				=> 'Minimum avatar dimensions',
 	'MIN_AVATAR_SIZE_EXPLAIN'		=> 'Width x Height in pixels.',
 ));