diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -28,3 +28,9 @@
    some minor documentation issues.
 
 Version 0.0.4: Updated for Dimensional 1.0.
+
+Version 0.0.5: Fixed bug in Monoid instance for Helmert. Created Semigroup
+   instance for Helmert.
+
+Version 0.0.6: Prevent attempted building on GHC 7.8 (it doesn't work)
+   and fix the build on 7.10 with a conditional semigroups dependency
diff --git a/geodetics.cabal b/geodetics.cabal
--- a/geodetics.cabal
+++ b/geodetics.cabal
@@ -1,5 +1,5 @@
 name:           geodetics
-version:        0.0.5
+version:        0.0.6
 cabal-version:  >= 1.10
 build-type:     Simple
 author:         Paul Johnson <paul@cogito.org.uk>
@@ -30,9 +30,11 @@
 library
   hs-source-dirs:  src
   build-depends:   
-                   base >= 4.6 && < 5,
+                   base >= 4.7 && < 5,
                    dimensional >= 1.0,
                    array >= 0.4
+  if !impl(ghc>=8.0)
+    build-depends: semigroups >= 0.9 && < 0.19
   ghc-options:     -Wall
   exposed-modules: 
                    Geodetics.Altitude,
@@ -61,19 +63,8 @@
                    array >= 0.4,
                    checkers
   hs-source-dirs:  
-                   src, 
                    test
   ghc-options:     -Wall -rtsopts
   other-modules:   
-                   ArbitraryInstances,
-                   Main,
-                   Geodetics.Altitude,
-                   Geodetics.Ellipsoids
-                   Geodetics.Geodetic,
-                   Geodetics.Grid,
-                   Geodetics.LatLongParser,
-                   Geodetics.Path,
-                   Geodetics.Stereographic,
-                   Geodetics.TransverseMercator,
-                   Geodetics.UK
+                   ArbitraryInstances
   Default-Language: Haskell2010