diff --git a/vasl_templates/webapp/static/help/index.html b/vasl_templates/webapp/static/help/index.html
index 5969f5b..a646b3e 100644
--- a/vasl_templates/webapp/static/help/index.html
+++ b/vasl_templates/webapp/static/help/index.html
@@ -304,6 +304,8 @@ or a <tt>width</tt> and/or <tt>height</tt> parameter to explicitly set the image
 
 <div class="info"> VASSAL caches images (which can't be turned off), so if you're making changes that don't seem to be having any effect, try restarting VASSAL. </div>
 
+<div class="warning"> You should avoid having spaces in image URL's, since VASSAL seems to have problems with them. </div>
+
 <a name="workflow">
 <h2> Suggested workflow </h2>