diff --git a/README.md b/README.md
index ae3337e..ea627e0 100644
--- a/README.md
+++ b/README.md
@@ -6,10 +6,12 @@ The class also allows you to query servers using RCON although this only works f
 
 [Minecraft](http://www.minecraft.net) also uses Source RCON protocol, and this means you can use this class to send commands to your minecraft server while having engine set to Source engine.
 
-**This library requires a [modern version](https://php.net/supported-versions.php) of PHP, so make sure you are using at least PHP 5.5 or newer.**
-
 **:warning: Please do not create issues when you are unable to retrieve information from a server, unless you can prove that there is a bug within the library.**
 
+## Requirements
+* [Modern PHP version](https://php.net/supported-versions.php) (5.5 or newer)
+* 64-bit PHP or [gmp module](https://secure.php.net/manual/en/book.gmp.php)
+
 ## Protocol Specifications
 * https://developer.valvesoftware.com/wiki/Server_queries
 * https://developer.valvesoftware.com/wiki/Source_RCON_Protocol
diff --git a/SourceQuery/SourceQuery.php b/SourceQuery/SourceQuery.php
index 2cba855..e3571b0 100644
--- a/SourceQuery/SourceQuery.php
+++ b/SourceQuery/SourceQuery.php
@@ -315,7 +315,7 @@
 					
 					if( PHP_INT_SIZE === 4 )
 					{
-						if( extension_loaded( 'gmp2' ) )
+						if( extension_loaded( 'gmp' ) )
 						{
 							$a = gmp_abs( $a );
 							$b = gmp_abs( $b );