diff --git a/inst/rmarkdown/templates/revealjs_presentation/resources/default.html b/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
index d888684..7fa2f49 100644
--- a/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
+++ b/inst/rmarkdown/templates/revealjs_presentation/resources/default.html
@@ -722,7 +722,7 @@
           transition: $chalkboard-transition$,
 $endif$
 $if(chalkboard-theme)$
-          theme: $chalkboard-theme$,
+          theme: '$chalkboard-theme$',
 $endif$
 $if(chalkboard-color)$
           color: $chalkboard-color$,