diff --git a/musicxml2.cabal b/musicxml2.cabal
--- a/musicxml2.cabal
+++ b/musicxml2.cabal
@@ -1,6 +1,6 @@
 
 name:                   musicxml2
-version:                1.6.2
+version:                1.7
 synopsis:               A representation of the MusicXML format.
 author:                 Hans Hoglund
 maintainer:             Hans Hoglund
@@ -26,8 +26,8 @@
                         type-unary,
                         reverse-apply,
                         xml,
-                        music-pitch-literal     == 1.6.2,
-                        music-dynamics-literal  == 1.6.2
+                        music-pitch-literal     == 1.7,
+                        music-dynamics-literal  == 1.7
     exposed-modules:    Music.MusicXml
                         Music.MusicXml.Time
                         Music.MusicXml.Pitch
diff --git a/src/Music/MusicXml/Time.hs b/src/Music/MusicXml/Time.hs
--- a/src/Music/MusicXml/Time.hs
+++ b/src/Music/MusicXml/Time.hs
@@ -79,6 +79,9 @@
 deriving instance Ord           Tempo
 deriving instance Num           Tempo
 deriving instance Enum          Tempo
+deriving instance Fractional    Tempo
+deriving instance Real          Tempo
+deriving instance RealFrac      Tempo
 deriving instance Show          Tempo