diff --git a/docs/envvars.html b/docs/envvars.html
index 2d9a2891144..6d79398e1df 100644
--- a/docs/envvars.html
+++ b/docs/envvars.html
@@ -50,8 +50,17 @@ sometimes be useful for debugging end-user issues.
    if the application generates a GL_INVALID_ENUM error, a corresponding error
    message indicating where the error occurred, and possibly why, will be
    printed to stderr.<br>
-   If the value of MESA_DEBUG is 'FP' floating point arithmetic errors will
-   generate exceptions.
+
+   For release builds, MESA_DEBUG defaults to off (no debug output).
+
+   MESA_DEBUG accepts the following comma-separated list of named
+   flags, which adds extra behaviour to just set MESA_DEBUG=1:
+   <ul>
+     <li>silent - turn off debug messages. Only useful for debug builds.</li>
+     <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>
+   </ul>
 <li>MESA_LOG_FILE - specifies a file name for logging all errors, warnings,
 etc., rather than stderr
 <li>MESA_TEX_PROG - if set, implement conventional texture env modes with