diff --git a/LDP/guide/docbook/PLD-Guide/installer-theory.xml b/LDP/guide/docbook/PLD-Guide/installer-theory.xml
index 6fdccb65..928a6239 100644
--- a/LDP/guide/docbook/PLD-Guide/installer-theory.xml
+++ b/LDP/guide/docbook/PLD-Guide/installer-theory.xml
@@ -1176,7 +1176,7 @@
 	      </listitem>
 	      <listitem>
 		<para>Sebastian Zagrodzki</para>
-		<para>The author if first working installer, called prowizorka.
+		<para>The author of the first working installer, called prowizorka.
 		  Also added support for console on serial port to bootdisk, and instruction how to use
 		  it (in this manual)</para>
 	      </listitem>