diff --git a/CHANGES b/CHANGES
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,9 @@
+Version 0.7.3.8 released 24 July 2010
+
+* Fixed MathML in Slidy and S5 exports.
+
+* Use languagesByFilename instead of languagesByExtension in isSource.
+
 Version 0.7.3.7 released 24 July 2010
 
 * Depend on pandoc >= 1.6, highlighting-kate >= 0.2.7.1
diff --git a/Network/Gitit/Export.hs b/Network/Gitit/Export.hs
--- a/Network/Gitit/Export.hs
+++ b/Network/Gitit/Export.hs
@@ -20,11 +20,12 @@
 -}
 
 module Network.Gitit.Export ( exportFormats ) where
-import Text.Pandoc
+import Text.Pandoc hiding (HTMLMathMethod(..))
+import qualified Text.Pandoc as Pandoc
 import Text.Pandoc.S5 (s5HeaderIncludes)
-import Text.Pandoc.Shared (escapeStringUsing)
+import Text.Pandoc.Shared (escapeStringUsing, readDataFile)
 import Network.Gitit.Server
-import Network.Gitit.Framework (pathForPage)
+import Network.Gitit.Framework (pathForPage, getWikiBase)
 import Network.Gitit.Util (withTempDir, readFileUTF8)
 import Network.Gitit.State (getConfig)
 import Network.Gitit.Types
@@ -112,20 +113,50 @@
 respondS5 :: String -> Pandoc -> Handler
 respondS5 pg doc = do
   cfg <- getConfig
+  base' <- getWikiBase
   inc <- liftIO $ s5HeaderIncludes (pandocUserData cfg)
+  let math = case mathMethod cfg of
+                 MathML       -> Pandoc.MathML Nothing
+                 WebTeX u     -> Pandoc.WebTeX u
+                 JsMathScript -> Pandoc.JsMath
+                                  (Just $ base' ++ "/js/jsMath/easy/load.js")
+                 _            -> Pandoc.PlainMath
+  variables' <- if mathMethod cfg == MathML
+                   then do
+                      s <- liftIO $ readDataFile (pandocUserData cfg) $
+                                "data"</>"MathMLinHTML.js"
+                      return [("mathml-script", s),("s5includes",inc)]
+                   else return [("s5includes",inc)]
   respondS "s5" "text/html; charset=utf-8" ""
     writeHtmlString
     defaultRespOptions{writerSlideVariant = S5Slides
-                      ,writerIncremental = True,
-                       writerVariables = [("s5includes",inc)]}
+                      ,writerIncremental = True
+                      ,writerVariables = variables'
+                      ,writerHTMLMathMethod = math}
     pg doc
 
 respondSlidy :: String -> Pandoc -> Handler
 respondSlidy pg doc = do
+  cfg <- getConfig
+  base' <- getWikiBase
+  let math = case mathMethod cfg of
+                 MathML       -> Pandoc.MathML Nothing
+                 WebTeX u     -> Pandoc.WebTeX u
+                 JsMathScript -> Pandoc.JsMath
+                                  (Just $ base' ++ "/js/jsMath/easy/load.js")
+                 _            -> Pandoc.PlainMath
+  variables' <- if mathMethod cfg == MathML
+                   then do
+                      s <- liftIO $ readDataFile (pandocUserData cfg) $
+                                "data"</>"MathMLinHTML.js"
+                      return [("mathml-script", s)]
+                   else return []
   respondS "slidy" "text/html; charset=utf-8" ""
     writeHtmlString
     defaultRespOptions{writerSlideVariant = SlidySlides
-                      ,writerIncremental = True}
+                      ,writerIncremental = True
+                      ,writerHTMLMathMethod = math
+                      ,writerVariables = variables'}
     pg doc
 
 respondTexinfo :: String -> Pandoc -> Handler
diff --git a/Network/Gitit/Framework.hs b/Network/Gitit/Framework.hs
--- a/Network/Gitit/Framework.hs
+++ b/Network/Gitit/Framework.hs
@@ -66,8 +66,8 @@
 import Data.ByteString.UTF8 (toString)
 import Data.ByteString.Lazy.UTF8 (fromString)
 import Data.Maybe (fromJust)
-import Data.List (intercalate, isPrefixOf, isInfixOf, (\\))
-import System.FilePath ((<.>), takeExtension)
+import Data.List (intercalate, isPrefixOf, isInfixOf)
+import System.FilePath ((<.>), takeExtension, takeFileName)
 import Text.Highlighting.Kate
 import Text.ParserCombinators.Parsec
 import Network.URL (decString, encString)
@@ -265,8 +265,7 @@
 
 isSourceCode :: String -> Bool
 isSourceCode path' =
-  let ext   = map toLower $ takeExtension path'
-      langs = languagesByExtension ext \\ ["Postscript"]
+  let langs = languagesByFilename $ takeFileName path'
   in  not . null $ langs
 
 -- | Returns encoded URL path for the page with the given name, relative to
diff --git a/gitit.cabal b/gitit.cabal
--- a/gitit.cabal
+++ b/gitit.cabal
@@ -1,5 +1,5 @@
 name:                gitit
-version:             0.7.3.7
+version:             0.7.3.8
 Cabal-version:       >= 1.2
 build-type:          Simple
 synopsis:            Wiki using happstack, git or darcs, and pandoc.