diff --git a/src/Text/Pandoc/Writers/HTML.hs b/src/Text/Pandoc/Writers/HTML.hs
index 6bc911fbd..5550db105 100644
--- a/src/Text/Pandoc/Writers/HTML.hs
+++ b/src/Text/Pandoc/Writers/HTML.hs
@@ -237,15 +237,14 @@ elementToHtml opts (Sec level num id' title' elements) = do
   let stuff = header'' : innerContents
   let slide = writerSlideVariant opts /= NoSlides && level == 1
   let titleSlide = slide && null elements
-  let classes = [theclass "titleslide" | titleSlide] ++
-                [theclass "slide" | slide]
+  let attrs = [prefixedId opts id' | writerSectionDivs opts] ++
+              [theclass "titleslide" | titleSlide] ++
+              [theclass "slide" | slide]
   let inNl x = nl opts : intersperse (nl opts) x ++ [nl opts]
   return $ if writerSectionDivs opts || slide
               then if writerHtml5 opts
-                      then tag "section" ! (prefixedId opts id' : classes)
-                                << inNl stuff
-                      else thediv ! (prefixedId opts id' : classes)
-                                << inNl stuff
+                      then tag "section" ! attrs << inNl stuff
+                      else thediv ! attrs << inNl stuff
               else toHtmlFromList $ intersperse (nl opts) stuff
 
 -- | Convert list of Note blocks to a footnote <div>.
diff --git a/tests/s5.basic.html b/tests/s5.basic.html
index 88ac22631..0658dcf4b 100644
--- a/tests/s5.basic.html
+++ b/tests/s5.basic.html
@@ -34,14 +34,14 @@
   <h3>Sam Smith<br/>Jen Jones</h3>
   <h4>July 15, 2006</h4>
 </div>
-<div id="first-slide" class="slide">
+<div class="slide">
 <h1>First slide</h1>
 <ul>
 <li>first bullet</li>
 <li>second bullet</li>
 </ul>
 </div>
-<div id="math" class="slide">
+<div class="slide">
 <h1>Math</h1>
 <ul>
 <li><span class="math">$\frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}$</span></li>
diff --git a/tests/s5.fancy.html b/tests/s5.fancy.html
index 0e10ae0b0..39188bb1e 100644
--- a/tests/s5.fancy.html
+++ b/tests/s5.fancy.html
@@ -235,14 +235,14 @@
   <h3>Sam Smith<br/>Jen Jones</h3>
   <h4>July 15, 2006</h4>
 </div>
-<div id="first-slide" class="slide">
+<div class="slide">
 <h1>First slide</h1>
 <ul class="incremental">
 <li>first bullet</li>
 <li>second bullet</li>
 </ul>
 </div>
-<div id="math" class="slide">
+<div class="slide">
 <h1>Math</h1>
 <ul class="incremental">
 <li><span class="LaTeX">$\frac{d}{dx}f(x)=\lim_{h\to 0}\frac{f(x+h)-f(x)}{h}$</span></li>