diff --git a/reference/openssl/functions/openssl-random-pseudo-bytes.xml b/reference/openssl/functions/openssl-random-pseudo-bytes.xml
index 923ece93b869..9b5c1969511e 100644
--- a/reference/openssl/functions/openssl-random-pseudo-bytes.xml
+++ b/reference/openssl/functions/openssl-random-pseudo-bytes.xml
@@ -64,6 +64,10 @@
    <function>openssl_random_pseudo_bytes</function> throws an <classname>Exception</classname>
    on failure.
   </para>
+  <simpara>
+   Throws a <exceptionname>ValueError</exceptionname> if <parameter>length</parameter>
+   is less than <literal>1</literal>.
+  </simpara>
  </refsect1>
 
  <refsect1 role="changelog">