diff --git a/Debugging-pdf.js.md b/Debugging-pdf.js.md
index f3d32e0..720a683 100644
--- a/Debugging-pdf.js.md
+++ b/Debugging-pdf.js.md
@@ -1,5 +1,5 @@
 ## Enabling
-As a safety precaution the debugging tools for the extension and the version of pdf.js bundled with firefox will require the user to set/create a pref in `about:config`:
+As a safety precaution the debugging tools for the extension and the version of pdf.js bundled with firefox will require the user to set/create a boolean pref in `about:config`:
 
 * Extension Version: `extensions.uriloader@pdf.js.pdfBugEnabled` setting (boolean `true`)
 * Mozilla Central(Firefox) Version: `pdfjs.pdfBugEnabled` setting (boolean `true`)