diff --git a/docs/envvars.html b/docs/envvars.html
index af1a30c..5dd7bab 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -60,6 +60,8 @@
      <li>flush - flush after each drawing command</li>
      <li>incomplete_tex - extra debug messages when a texture is incomplete</li>
      <li>incomplete_fbo - extra debug messages when a fbo is incomplete</li>
+     <li>context - create a debug context (see GLX_CONTEXT_DEBUG_BIT_ARB) and
+         print error and performance messages to stderr (or MESA_LOG_FILE).</li>
    </ul>
 <li>MESA_LOG_FILE - specifies a file name for logging all errors, warnings,
 etc., rather than stderr