diff --git a/help/titan_main.html b/help/titan_main.html
index 6580125e78fa5f5dd991fd3d80765e35a44a05dc..e274aa0c43ae668f6d17cad6522e7b0847a4fa84 100644
--- a/help/titan_main.html
+++ b/help/titan_main.html
@@ -109,7 +109,7 @@
     <p align="left"><a href="docs/ReferenceGuide.pdf" target="_blank">Programmer's Technical Reference for TITAN</a>
     </li>
     <li>
-    <p align="left"><a href="docs/ApiGuide.pdf" target="_blank">API Technical Reference for TITAN</a>
+    <p align="left"><a href="docs/Apiguide.pdf" target="_blank">API Technical Reference for TITAN</a>
     </li>
     <li>
     <p align="left"><a href="docs/installationguide.pdf" target="_blank">TITAN Installation Guide</a>