diff --git a/functions/gmp.xml b/functions/gmp.xml
index 882038c18b..8b0e659e21 100644
--- a/functions/gmp.xml
+++ b/functions/gmp.xml
@@ -86,6 +86,25 @@ print gmp_strval (fact (1000)) . "\n";
       </programlisting>
      </example>
     </para>
+
+    <warning>
+     <para>
+      If you want to explicitely specify an integer, do not use
+      <literal>gmp_init(12378473895798475827348979342)</literal>,
+      since first the integer-literal will be interpreted,
+      resulting in an 
+      <link linkend="language.types.integer.overflow">overflow</link>
+      and thus in zero, and then gmp_init is called with that 
+      zero as argument.
+      <!-- TODO: wrong, it will be converted to float (type-jug), which
+      will lead to loss of precision. -->
+     </para>
+     <simpara>
+      Instead, use 
+      <literal>gmp_init('12378473895798475827348979342')</literal>
+     </simpara>
+    </warning>
+    
     <note>
      <para>
       It is not necessary to call this function if you want to use